This updates the RB.ReviewRequest object in JavaScript for the new API.

One of the new key concepts in this change and the upcoming changes
is the introduction of a new ready() function for the objects. This works
just like jQuery's ready() function. Any call that operates on a
RB.ReviewRequest should wrap it in a review_request.ready() call. This will
guarantee that the state of the review request has been loaded. This may
include some variables, child hrefs, and more.

ready() will only perform a load of the resource the first time it's called.

As a whole, the combined commits for the overall webui change pass most unit tests. The remaining ones are still being looked at, but are not relevant to this particular change.