Adds a pod spec, so that this component can be used in projects that use cocoa pods.

Hi there,

This pull request is quite a basic one, but takes some explaining - the file that I've added allows this project to be used with CocoaPods.

Now in case you don't know what CocoaPods is, it's a library dependency management system for Objective-C developers - think an equivalent of Gems in Ruby or Maven in Java. For me, it certainly makes my iThing development much easier when it comes to using third party libraries as I don't need to worry about which frameworks to add or ARC vs. non-ARC or which files are classes & which are tests, sample projects, etc.

They also provide a central repository of podspecs - if you add this file over there, not only will people not have to go into the effort of adding this repository to use this project in CocoaPods, but you also get an entry on their website & a mention on their twitter feed automatically :-). I'll leave the honours of adding your podspec down to you.

If you do accept this pull request, there will be some refinements to make before they accept it into their central repository - for example, you'll need to tag a commit on here & refer to that rather than the specific commit I'm using - the version number should also reflect this tag.

Anyway, thank you for reading - feel free to try out & read CocoaPods up properly before accepting this pull request if you're not familiar with it.