Added Support for Form Parameters to Request Method

I've added support for form parameters to the request method:

**the old API contract still works**:

```javascript
api.request('GET', '/service/hidden/version/10/backend', function(err, response) {
})
```

**You can now also pass in the form parameters**:

```javascript
api.request('PUT', '/service/hidden/version/10/backend/' + encodeURIComponent('foo host'), {
  auto_loadbalance: '1'
}, function (err, res) {
})
```

If you're alright with these changes, mind pinging me when you've published a new version of the library to npm?