Update Review Bot to use the new web API.
Review Request #6192 — Created Aug. 2, 2014 and submitted
This updates the Review Bot extension to work with tool profiles instead of
tools. Also, upon completion of a review, the workers will now update the
corresponding tool execution object with a 'succeeded' status and the completed
review as a JSON blob, before publishing the review on Review Board.
Went through several manual execution scenarios, listed in detail in /r/6139.