Added Podspec

Hi Alex,

A great project you have here. We wanted to use it in our application using [Cocoapods](http://cocoapods.org/) so I created a podspec.

Here it is if you'd like to include it so others can use your project in Cocoapods.
Cocoapods will recommend that you tag a release and update the Podspec accordingly. I can help with this if you'd like to tag a 1.0.0.

Thanks for creating this!
- Viet Pham