Adds AMD wrapper

Hi @rmm5t!

First, awesome plugin!  

Second, I ran into a small problem tonight including it in my project where I use both RequireJS and jQuery in no conflict mode.  The software I'm uses RequireJS to compile a single JS file that can be embedded on an end users website. Because of that, I compile in my own version of jQuery in noconflict mode as well as my required plugins.  In order for for this to work, jQuery plugins need to allow RequireJS to inject the jQuery object when the plugin is loaded in order to keep it out of the global namespace.  I made some small changes that allow this to work.

Cheers,
Brian