tweak to the files view ui

Very small tweak to the files view UI, to make folder line up visually with sibling files. This makes it easier to scan the files view and know the relationship between files.

![screen shot 2014-05-21 at 9 59 25 am](https://cloud.githubusercontent.com/assets/1269969/3043741/9100855a-e109-11e3-8b96-53fd29cf254f.png)

@dinhviethoa