Allow request() method to return curlinfo array instead of response

Very small change, but quite helpful when working with the modRestCurlClient. If the param "returninfo" is set to true via the $options array like

```
$this->modx->getService('getfile','rest.modRestCurlClient');
$response = $this->modx->getfile->request($options['url'], $options['path'], $options['method'], $options['params'], $options['options'] = array('returninfo' => 1));
```
the response contains all information about the request from curl_getinfo()