Initial privileged loader commit

This adds a functioning privileged loader app, with zero frills thus far.  Only firefox os has been tested, but likely only minor changes would be needed to get it working on other platforms.
Looks like we are just using jQuery for this single XHR request. We could bring in browserify and a build step to give you access to the `xhr` module or you could just add the functionality manually. This is likely to stay pretty thin, so I'd be fine to just bring in the abstraction manually for now while we are trying to get the basics in-place. :smile: