Trivial fix for parsing ReviewGroup payloads.

My recent change to enable parsing ReviewGroup payloads didn't
transition correctly between my repositories. I ended up placing the
'rspNamespace' on the wrong object. Now parsing works correctly again.
Fix a bunch of pyflakes warnings.

Fix up things that have snuck in over the past few months. Trivial changes.

Testing done: Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/5733/