Controller filters can shortcut request lifecycle by returning a Response


  * If a before filter returns it, both the action and the after filters will be skipped (as well as any remaining
  * If an after filter returns it, any remaining after filters in the block will be skipped.
  * There is no way for the action result to skip the :after filters.

Closes #21
Signed-off-by: Josep M. Blanquer <blanquer@rightscale.com>
when a class including controller does not implement any definition. It's not a good pattern to do that, but until we solve the inheritance (and perhaps break the filters out of the controller module we need this)