Add AMD support

This pull request adds AMD support using the template supplied by the UMDJS project: https://github.com/umdjs/umd/blob/master/amdWebGlobal.js

This template doesn't changed the existing behaviour. However those who do have an AMD loader, like requirejs, can now use this plugin directly without shimming.
Update minified file
Merge pull request #19 from xzyfer/patch-1

Add AMD support thanks to xzyfer.