Tweaks in tree-view

Hello there. First, thanks for this great theme.
The bug that I found was that if one file has a long name, the tree-view would be huge and with no option to resize. 
I've made some minor tweaks in padding and change the color for modified (not selected as mentioned in the commit) items (from brown to blue).

Let's wait until the node-webkit has support for transparency (https://github.com/rogerwang/node-webkit/issues/132) and then implement the CSS blur effect on the tree-view background.

Feel free to accept or reject this pull.