Avoid "No route found for OPTIONS" errors

To [short circuit  the Silex controller](http://silex.sensiolabs.org/doc/middlewares.html#short-circuiting-the-controller) we must return a Response and it seems calling $response->send() alone is not enough as it is generating an MethodNotAllowedHttpException.

The change proposed avoid these exceptions.
Merge pull request #7 from websoftix/patch-1

Avoid "No route found for OPTIONS" errors