GCI-48: Theming

Improves look and feel of iOS add. Adjusts colors, and adds activity indicator for network operations:

![screen shot 2014-12-09 at 7 36 32 am](https://cloud.githubusercontent.com/assets/5162342/5358869/1d0866e8-7f76-11e4-8247-3f60ac44ad51.png)
![screen shot 2014-12-09 at 7 34 25 am](https://cloud.githubusercontent.com/assets/5162342/5358870/1d100c72-7f76-11e4-8fca-d41c55b84118.png)