Make the scrollbar prettier

http://gfycat.com/SpiffyScaryBlackfootedferret

New:
![screen shot 2014-12-18 at 3 48 07 pm](https://cloud.githubusercontent.com/assets/81969/5495640/4e2cfd3e-86cd-11e4-9ee8-f11b35d1e9da.png)

Old:
![screen shot 2014-12-18 at 3 48 47 pm](https://cloud.githubusercontent.com/assets/81969/5495646/634d1de8-86cd-11e4-8016-15bf4881b305.png)