Basic Skeleton for SimpleGame

- AppController is a singleton that controls the lifetime of
  the GameController and the DisplayController.

- GameController will control all of the game logic. It owns
  a level and will eventually own the player.

- Level and Room are part of the data layer. They should not
  need to
  know anything about DisplayController or GameController

- DisplayController will control UI for the game.

- Debug Controller will handle debug logging

- RandomNumberGenerator.h is just a header containing the random
  seed and a way for classes to simply get a random number.