Tweak the vertical alignment on img in footer

Before:

![screen shot 2014-07-02 at 8 36 14 pm](https://cloud.githubusercontent.com/assets/124661/3465337/7b0bdf12-0263-11e4-9ef8-69a37a26ac79.png)

After:

![screen shot 2014-07-02 at 8 35 54 pm](https://cloud.githubusercontent.com/assets/124661/3465338/7f98f1b4-0263-11e4-830e-409bea0def27.png)