Windows Support

This adds the ability to run Kart and load games on Windows (win32) as well as OS X (darwin).

* Cleans up the way paths were being built
* Adds retroarch configs into Kart that will be run, per platform

![screen shot 2014-05-31 at 11 41 48 pm](https://cloud.githubusercontent.com/assets/260/3140801/24b008f6-e93f-11e3-84ca-fb255110a1b2.png)