Updated CAS controller to remove RubyCAS::Filter.client

As far as I can tell the RubyCAS-client-rails gem is broken under rails 3+ (or at least 3.1). In fact RubyCAS-client works great in all aspects WITHOUT RubyCAS-client-rails. This was the only issue I had run into and removing it resolved all of my problems.

If this is necessary in other places please make a suggestion to resolve this issue as I don't want to break other users of this gem.