Update footer by replacing navigation with credits

# Before
![screen shot 2013-08-31 at 1 12 39 pm](https://f.cloud.github.com/assets/95995/1062933/d8179726-1279-11e3-93b9-7f9c63efd9e2.png)
# After
![screen shot 2013-08-31 at 1 13 06 pm](https://f.cloud.github.com/assets/95995/1062934/e08b3fde-1279-11e3-82e5-5532dce6d527.png)