Send SMS API

 * Removes SurfnetStepupGatewayBundle and moves resources to application level
 * Creates SurfnetStepupGatewayApiBundle
Still unsure whether or not I like this. Personally I have a strong preference for putting the full URL in control of the definer, not of the "includer" so to say. This is a different story for vendor-controller URLs, but this is fully app-controlled. Thoughts?