Clean up and document the Review Board file.

Review Request #154 — Created Nov. 16, 2016 and updated

Review Board
This is a cleanup change for bringing back to our modern coding
standards and to help with maintenance. It adds docstrings where
missing, removes the outdated support, switches strings to
single quotes, appends "Command" to all command classes, removes the old
hack for installing data files on macOS (which no longer appears to be
needed for modern versions of Python), and fixes up the setup() call to
be better organized and use a more sane indent level. The package also
has a better description.

Testing Done:
Built different package types and inspected them.

Tested that each entrypoint loaded, that all command line scripts were
registered, and that all configuration forms (authentication settings
and repositories) listed each option we support.

Compared the list of installed files before and after the `install_data`
hack. Verified that Python 2.7 isn't impacted by the old bug that the
classes were for. (Django has also removed their support, and it doesn't
look like Python 2.6 should be impacted either.)

Reviewed at