Symfony integration

As symfony has it's own session management and uses the HttpFoundation component to send the response (and the headers). We can't just exit in the middle of the request. 

This PR makes this possible assigning to response object to ```symfony_response``` in the config. This will be adjusted by Opauth and the controller can return this. 

This will make this package usable for all frameworks using the HttpFoundation component

If you have any remarks/notes to my changes, let me know.