docs(cached): Deprecate unnamed caches

Name is now listed as a required parameter, but current functionality is unchanged.
Add deprecation warning for caches with non-string names. (They're probably a mistake anyway.)

README.md

@@ -123,8 +123,8 @@ cached('myStuff');
 
 Creates a new named cache or returns a previously initialized cache.
 
-* **name:** A meaningful name for what is in the cache, default: `"default"`. This will also be used as a key-prefix. If the name is `"cars"`, all keys will be prefixed with `"cars:"`
-* **options:**
+* **name:** (required) A meaningful name for what is in the cache. This will also be used as a key-prefix. If the name is `"cars"`, all keys will be prefixed with `"cars:"`
+* **options:** (optional)
   * **backend:** An object that has at least a `type` property. If no backend is configured, the cache will run in "noop"-mode, not caching anything. All other properties are forwarded to the backend, see [using different backends](#supported-backends) for which backend types exist and what options they support.
   * **defaults:** Defaults to apply for all cache operations. See `Cache.setDefaults`
 

lib/cached.js

@@ -33,13 +33,20 @@
 
 var Bluebird = require('bluebird');
 var _ = require('lodash');
+var util = require('util');
 
 var Cache = require('./cache');
 
 var namedCaches = Object.create(null);
 
+var getName = util.deprecate(function getName(name) {
+  return name || 'default';
+}, 'Unnamed caches and caches with non-string names are deprecated.');
+
 function cached(name, options) {
-  name = name || 'default';
+  if (typeof name !== 'string') {
+    name = getName(name);
+  }
 
   if (!(name in namedCaches)) {
     namedCaches[name] = cached.createCache(_.extend({