Adding demo project

I created a basic demo project that will make this project accessible with `cocoapod try`. It will also make it easier to visualize color changes/text changes that we make to this library. We definitely need to add more to this project to flesh it out some more, but I think having the Fonts and the Colors are a good start.

Here's some screenshots of the very basic UI:

![image](https://cloud.githubusercontent.com/assets/437043/3620727/32dc17bc-0e06-11e4-99f7-74297ecb4cf3.png)

![image](https://cloud.githubusercontent.com/assets/437043/3620729/361f7f68-0e06-11e4-85b9-fab9d25087cd.png)

![image](https://cloud.githubusercontent.com/assets/437043/3620732/3a44486c-0e06-11e4-9c72-1f9084f3e1b4.png)

same comment as the comment on ColorDetails:

https://github.com/wordpress-mobile/WordPress-iOS-Shared/pull/18/files#discussion_r15129505