Use factory file so JS used by studio_xblock_wrapper.html goes through RequireJS Optimizer

The code change is up on my sandbox (http://studio.cahrens.m.sandbox.edx.org/course/validation/validation/validation).

You can see there that the factory file is loaded instead of the individual model and view files.
Note to reviewers: xblock_url (Python variable) will be either None or a string. bool(xblock_url) will return False for both None and an empty string, which is what I want in this case.