Movement command, Animation State

Addresses #6 
Everything works as far as I can tell, but I expect the style will need tons of fixing, since I'm new to javascript. I don't mind making lots of changes, so go ahead and tear this apart.
In addition to the MovementCommand and AnimationState classes, It made sense to me to make a Coordinate struct that represents coordinate pairs ({x: __, y: __}). Of course, we didn't specifically talk about that in the original plans, so I can remove it if you don't like it. 
General practice for javascript objects is not to specify them all in the constructor: instead, as in `ApplicationController`, we should specify this outside of the constructor like `MovementCommand.prototype.getStartPosition = function () {...}`. See [here](http://bonsaiden.github.io/JavaScript-Garden/#object) for a more in depth explanation of objects and how prototypical inheritance works in javascript and let me know if you have any questions! You could also open an issue with the "question" tag so that others can benefit from it as well.