Added an input class (with tiny command classes) and added controller support!

I redesigned the input handling to follow [this](http://gameprogrammingpatterns.com/command.html) pattern somewhat . Hopefully it will make it easier to remap controls if we want to do that in the future. I also built in rough controller support that we could show off at the demo.

* Bindings
    * Left-Stick: Movement
    * Right-Stick: Gaze
    * Right-Bumper: Punch

Finally, Monogame has a weird issue where is doesn't incorporate the correct .dll's for controller support. I had to add those to my output folder as per [this](http://monogame.codeplex.com/discussions/434356) to get the controller to connect in the first place.