Issue #19: Remove documentation for attachment size constraints

The attachment size constraints (i.e. `attachmentConstraints.maximumIndividualSize`, `attachmentConstraints.maximumTotalSize` and the `attachmentReference` validation type's `maximumSize`) cannot be applied correctly to CouchDB documents due to a performance optimization that makes it impossible for a validation function to determine the size of an attachment as it is being created ([more info](apache/couchdb#1320)). The documentation has been updated to remove mention of the attachment size constraints, since they cannot be enforced. They will be removed from the code altogether in the future.

README.md

@@ -227,10 +227,8 @@ Additional properties that provide finer grained control over documents:
 * `cannotReplace`: (optional) As with the `immutable` constraint, the document cannot be replaced after it is created. However, this constraint does not prevent the document from being deleted. Note that, even if attachments are allowed for this document type (see the `allowAttachments` document constraint for more info), it will not be possible to create, modify or delete attachments in a document that already exists, which means that they must be created inline in the document's `_attachments` property when the document is first created. In addition to a static value (e.g. `cannotReplace: true`), this constraint may also be assigned a value dynamically via a function (e.g. `cannotReplace: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Defaults to `false`.
 * `cannotDelete`: (optional) As with the `immutable` constraint, the document cannot be deleted after it is created. However, this constraint does not prevent the document from being replaced. In addition to a static value (e.g. `cannotDelete: true`), this constraint may also be assigned a value dynamically via a function (e.g. `cannotDelete: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Defaults to `false`.
 * `allowAttachments`: (optional) Whether to allow the addition of [file attachments](http://docs.couchdb.org/en/latest/intro/api.html#attachments) for the document type. In addition to a static value (e.g. `allowAttachments: true`), this constraint may also be assigned a value dynamically via a function (e.g. `allowAttachments: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Defaults to `false` to prevent malicious/misbehaving clients from polluting the database with unwanted files. See the `attachmentConstraints` constraint and the `attachmentReference` validation type for more options.
-* `attachmentConstraints`: (optional) Various constraints to apply to file attachments associated with a document type. Its settings only apply if the document definition's `allowAttachments` constraint is `true`. In addition to a static value (e.g. `attachmentConstraints: { }`), this constraint may also be assigned a value dynamically via a function (e.g. `attachmentConstraints: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Additional parameters:
+* `attachmentConstraints`: (optional) Various constraints to apply to file attachments associated with a document type. Its settings only apply if the document definition's `allowAttachments` constraint is `true`. In addition to a static value (e.g. `attachmentConstraints: { }`), this constraint may also be assigned a value dynamically via a function (e.g. `attachmentConstraints: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). NOTE: the only way to (indirectly) limit the size of file attachments (and documents) is to set the global CouchDB configuration option [`httpd/max_http_request_size`](http://docs.couchdb.org/en/latest/config/http.html#httpd/max_http_request_size) ([more info](https://github.com/apache/couchdb/issues/1320)). Additional parameters:
   * `maximumAttachmentCount`: (optional) The maximum number of attachments that may be assigned to a single document of this type. In addition to a static value (e.g. `maximumAttachmentCount: 2`), this constraint may also be assigned a value dynamically via a function (e.g. `maximumAttachmentCount: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Unlimited by default.
-  * `maximumIndividualSize`: (optional) The maximum file size, in bytes, allowed for any single attachment assigned to a document of this type. In addition to a static value (e.g. `maximumIndividualSize: 256`), this constraint may also be assigned a value dynamically via a function (e.g. `maximumIndividualSize: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Unlimited by default.
-  * `maximumTotalSize`: (optional) The maximum total size, in bytes, of _all_ attachments assigned to a single document of this type. In other words, when the sizes of all of a document's attachments are added together, it must not exceed this value. In addition to a static value (e.g. `maximumTotalSize: 1024`), this constraint may also be assigned a value dynamically via a function (e.g. `maximumTotalSize: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Unlimited by default.
   * `supportedExtensions`: (optional) An array of case-insensitive file extensions that are allowed for an attachment's filename (e.g. "txt", "jpg", "pdf"). In addition to a static value (e.g. `supportedExtensions: [ 'png', 'gif', 'jpg' ]`), this constraint may also be assigned a value dynamically via a function (e.g. `supportedExtensions: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). No restriction by default.
   * `supportedContentTypes`: (optional) An array of content/MIME types that are allowed for an attachment's contents (e.g. "image/png", "text/html", "application/xml"). In addition to a static value (e.g. `supportedContentTypes: [ 'image/png', 'image/gif', 'image/jpeg' ]`), this constraint may also be assigned a value dynamically via a function (e.g. `supportedContentTypes: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). No restriction by default.
   * `requireAttachmentReferences`: (optional) Whether every one of a document's attachments must have a corresponding `attachmentReference`-type property referencing it. In addition to a static value (e.g. `requireAttachmentReferences: true`), this constraint may also be assigned a value dynamically via a function (e.g. `requireAttachmentReferences: function(newDoc, oldDoc) { ... }`) where the parameters are as follows: (1) the new document (if deleted, the `_deleted` property will be `true`) and (2) the document that is being replaced (if any; it will be `null` if it has been deleted or does not exist). Defaults to `false`.
@@ -342,7 +340,6 @@ Validation for simple data types (e.g. strings, booleans, integers, floating poi
 * `attachmentReference`: The value is the name of one of the document's file attachments. Note that, because the addition of an attachment is often a separate CouchDB API operation from the creation/replacement of the associated document, this validation type is only applied if the attachment is actually present in the document. However, since the validation function is run twice in such situations (i.e. once when the _document_ is created/replaced and once when the _attachment_ is created/replaced), the validation will be performed eventually. The top-level `allowAttachments` document constraint should be `true` so that documents of this type can actually store attachments. Additional parameters:
   * `supportedExtensions`: An array of case-insensitive file extensions that are allowed for the attachment's filename (e.g. "txt", "jpg", "pdf"). Takes precedence over the document-wide `supportedExtensions` constraint for the referenced attachment. No restriction by default.
   * `supportedContentTypes`: An array of content/MIME types that are allowed for the attachment's contents (e.g. "image/png", "text/html", "application/xml"). Takes precedence over the document-wide `supportedContentTypes` constraint for the referenced attachment. No restriction by default.
-  * `maximumSize`: The maximum file size, in bytes, of the attachment. Takes precedence over the document-wide `maximumIndividualSize` constraint for the referenced attachment. Unlimited by default.
 
 ##### Complex type validation