Fixes gitignore to ignore directories properly

Using the `DIR/*` format _technically_ works in git. But what this is REALLY saying is ignore first-level files in the `DIR` directory. This will cause software that reads the .gitignore file to not ignore stuff like `DIR/app/stuff.js`.

![screenshot 2014-12-11 19 32 28](https://cloud.githubusercontent.com/assets/2192970/5406347/a8cdd674-8177-11e4-9e27-686d036bd2a1.png)

http://stackoverflow.com/a/8783675/1585343
http://git-scm.com/docs/gitignore