When starting a new Review Bot worker process, Review Bot will now log

some information on the configuration. This lists the available tools,

the ones missing dependencies, the ones that require repository

configuration, and the available repositories. URLs for the relevant

sections in the manual are also provided.
This replaces the default Celery startup information, which, while

somewhat interesting, isn't generally useful for Review Bot. We can only

outright replace it with Celery 4+ on Python 3. On Python 2.7, the old

Celery banner will still display.
The logging is now done through a new root logger, which just uses

"Review Bot" as the name, rather than a module path. The configuration

code uses this logger as well, since the logging there ties more into

general startup.

Ran Review Bot with Python 2.7 and 3.x. Verified the details of the

startup information. Verified that the Celery banner didn't dsiplay

on 3.x.
Unit tests pass.