Fixed status code errors by calling _process_options

Needed to use the `_process_options` method explicitly because the overriding of `render_to_body` in the `ControllerAdditions` module removes it from the call chain.

Should resolve https://github.com/apotonick/roar-rails/issues/71
That sounds better, when I wrote this there was no AMS and I was too lazy to push changes to Responders as they were working differently back then.

If you're up to change the roar-rails responder, I will buy you beers!