Tests: Replace resource loader with AMD

:boom: WIP...

Pulll request's goal is to AMDify tests for 1.12.0 release and address part of http://bugs.jqueryui.com/ticket/10119.


I'm in favor of using RequireJS' css plugin as well. We can preserve the ability to run tests against source and minified files if we need it.

@scottgonzalez is the `?min` functionality something we actively use? I had no idea that existed and a bunch of tests fail when I use it.