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.


- qunit: I defer the question to @jzaefferer, can we load qunit using AMD reliably?
- swarminject: it's a helper that conditionally writes a script tag pointing to `http://swarm.jquery.org/js/inject.js` + a random variable. In the AMD world, this could be accomplished by using a plugin. It goes into the same discussion of https://github.com/jquery/jquery-ui/pull/1335#discussion_r17020552.
+ helper/jquery.js: the same as above. In the AMD world, this should be transformed into an AMD plugin. Goes into the https://github.com/jquery/jquery-ui/pull/1335#discussion_r17020552 category.