Chain-able interface

Still requires documents changes.

There are some inconsistencies in the existing api, so this is a complete overhaul of the interface used with the GoInstant v1 REST API.

Short example:

```js
var GoInstant = require('goinstant-rest').v1;
var client = new GoInstant({
  client_id: 'my-client-id',
  client_secret: 'my-client-secret'
});

// Getting a key value
client.keys('/my/key/path', {
  room_name: 'lobby',
  app_name: 'my-application'
}).get(function(err, res, value) {
});

// Getting an app with the ID 1
client.apps(1).get(function(err, res, app) {
});
```