Support to pageToken as youtube webService

I liked a lot how did you implemented that, but unfortunately didn't work with me (I'm using youtube, and youtube API uses pageToken instead with normal page)

Weel that's my code which I implemented pageToken and page as numbers, if you add to your source code I'll be very glad.

Also I added a .podspec file, which allows you to use cocoapods for real, and what you need to do is do a commit with a tag "1.1.0", and fork CocoaPods/Specs and add NMPaginator there, so it'll work :)

Hope helped to improve your code