Completely overhaul test RP. One page, all APIs.

Still needs CSS and returnTo love, but should be much more functional than
the existing test RP.

Basically, I wanted a single page where I could test all of the APIs, unexpected interactions, etc.

This does that.
Not sure if it's worth it, but it'd be nice if we could maybe add Grunt to this repo and throw a few random linting tasks like JSHint (which I think may be handled in a mocha test or something, IIRC), and JSONLint, and HTMLLint, etc.

Catching things like `<ol></li>` is very hard to do manually in a PR, but Grunt+Travis will catch them pretty easily.