Adds a .podspec file to be added to CocoaPods

You should add a podspec so that iOS developers using CocoaPods for dependency management can add BugSnag (it's just like Ruby Bundler but for Mac/iOS). If you choose to merge this, you should fork the CocoaPods Specs repository and make a pull request there to add the BugSnag repository (after which they give you push access).

On the .podspec: 
They prefer using git tags, but allow you to use git commit hashes, too (that's what I included in the .podspec). I included all the files in the Unity and Bugsnag Plugin folders. I did not specify which files were public, so by default all included files will be public. You may want to include a dependency on a JSON pod -- I'm not sure if there's a way to conditionally include a pod but I'm looking into it. Either way, I tested the podspec in a sample project and everything worked fine (I declared a framework dependency on SystemConfiguration.framework, which fixes the issue I emailed you about).

Since you've used Ruby gems you know how convenient this would be. As an advantage to you, CocoaPods makes it much easier for developers to automatically get the latest version of BugSnag (just like with Ruby bundler).

Resources:
http://cocoapods.org/
https://github.com/CocoaPods/Specs
http://nsscreencast.com/episodes/5-cocoapods