Convert the Bower dist file into a CommonJS and AMD compatible module

The tests all pass, and the ember-data-factory-guy.js file in dist/ now declares itself as a CommonJS and AMD module that can be required by other packages.

It's a little bit hacky, and still creates the `window.FactoryGuy` global, but doesn't create any others. This is (iirc) a backwards compatibility breaking change for the Bower package, so it should probably be released as 0.8.0 or something like that. I left the gem alone, since if you're using JS libraries from a gem, you probably aren't using AMD and don't care about global variables.