Visual Update

This begins to bring DOCter more in line with current visual standards and adds a `brand_color` variable to easily swap the CFPB green with another color.

![screen shot 2014-04-22 at 8 22 01 am](https://cloud.githubusercontent.com/assets/212533/2764713/73a9c6c6-ca19-11e3-800b-e3460993d601.png)