feat: add gotOptions constructor options

This allows the user to pass optional options through to the `got` instance. For instance, users can now connect via proxies.

Here is an example using [`caw`](https://github.com/kevva/caw), as further described in [sindresorhus/got#435](sindresorhus/got#435 (comment)) and originally brought up in [sindresorhus/got#79](sindresorhus/got#79).

```js
import Cloudflare from 'cloudflare':
import caw from 'caw';

const cf = new Cloudflare({
  email: '[email protected]',
  key: '<your API key here>',
  gotOptions: {
    agent: caw({ protocol: 'https' }) // Cloudflare API is HTTPS only
  }
});
```

README.md

@@ -23,7 +23,8 @@ the [My Account][my-account] page in the Cloudflare dashboard.
 ```javascript
 var cf = require('cloudflare')({
   email: '[email protected]',
-  key: 'your Cloudflare API key'
+  key: 'your Cloudflare API key',
+  gotOptions: {} // options passed to `got`, like a HTTP agent for proxying
 });
 ```
 
@@ -71,4 +72,4 @@ async function getZoneStatus(id) {
     * `purgeCache(zoneId, params)`
 * user
     * `read()`
-    * `edit(params)`
+    * `edit(params)`

index.js

@@ -14,10 +14,11 @@ var resources = {
 };
 
 var Cloudflare = auto(prototypal({
-  constructor: function (auth) {
+  constructor: function (options) {
     var client = new Client({
-      email: auth && auth.email,
-      key: auth && auth.key
+      email: options && options.email,
+      key: options && options.key,
+      gotOptions: options && options.gotOptions
     });
 
     Object.defineProperty(this, '_client', {

lib/Client.js

@@ -28,7 +28,7 @@ module.exports = prototypal({
   constructor: function (options) {
     this.email = options.email;
     this.key = options.key;
-    this.getter = new Getter(options);
+    this.getter = new Getter(options && options.gotOptions);
   },
   request: function (requestMethod, requestPath, data, opts) {
     var uri = 'https://api.cloudflare.com/client/v4/' + requestPath;

lib/Getter.js

@@ -4,8 +4,11 @@ var assign = require('object-assign');
 var got = require('got');
 
 module.exports = prototypal({
+  constructor: function (options) {
+    this.options = options || {};
+  },
   got: function (uri, options) {
-    options = assign({}, options);
+    options = assign({}, this.options, options);
 
     return got(uri, options);
   }