Hallas/progress loader

This is a progress loader that uses a sprite and a mask to create a loading look and feel

Complete with callbacks for everything you need done while loading stuff in the background
Doesn't seem like you're right about the return statement, the closure returns the value of the last statement even so..

![screen shot 2014-08-08 at 11 45 56](https://cloud.githubusercontent.com/assets/404172/3858962/1b332d76-1f13-11e4-95b8-ec761e328b89.png)