[Add] UI7Kit

UI7Kit is a GUI toolkit to implement iOS7 look & feel UIKit under iOS5/iOS6. It is also supported that patching UIKit to UI7Kit in runtime.

----

Question about spec policy.
I started this project and it is hard to use this library without cocoapods.
This project is very immature yet. Can I push this project to cocoapods?
Does this violate cocoapods spec policy?