Do some clean-up on the ReviewBot worker code.

Review Request #8433 — Created Sept. 24, 2016 and submitted — Latest diff uploaded

Information

ReviewBot
master
e13d365...

Reviewers

This change adds unicode_literals, docstrings, and does some cleanup for the
worker code. I haven't done docstrings for the individual tools because I got
lazy.

Tested that workers still responded correctly.