Setup observer pattern for keyboard input. Also added messaging to a couple of the key classes, still need to refine and improve that process. Make sure not to overuse the concept (use inheritance / composition when it makes sense)
Changed menu to observer pattern
I think messaging is done, at least for now. I could probably do a bunch of cleanup, but must of it woudln't be messaging, such as pulling Leaderboard stuff out of SceneManager
Merge pull request #12 from jcbrock/messaging

Adding messaging and observer pattern in a couple places