Git diff color support.

Loving the color scheme so far! Great work! <3

I'm was having a little issue with diff view, I use the [Git](https://sublime.wbond.net/packages/Git) package to handle some of my git operations, the most useful so far is git diff.

I picked colors that were already used on the theme, let me know I you want to change something.

![sublime text](https://cloud.githubusercontent.com/assets/519481/2539542/46b45b4a-b5c9-11e3-93de-03ff57f16104.png)