Protected Attributes -> Strong Parameters

This pull request removes the protected attributes gem from the Gemfile and implements strong parameters for every resource in the project. (in addition to refactoring of many controllers and re-aliasing before filters to before action and other minor style changes)
Also, why would you need to pass `:user_ids` to a user update? Maybe I'm just not clear on how HABTM associations work, but since we're updating a specific user then we already know the `user_id` part of the association...