Add a setting for all review tools to skip posting a review if there were no files processed.  I'm not a big fan of the variable naming, it seems confusing, but I couldn't think of better ones. Suggestions are welcome.
I've been using this for a while locally and finally polished it up a bit for review.

I have just the PEP8 and pyflakes bots enabled.

Setting defaults to off

Posting a powershell file results in a review posted.
Posting a python file results in a review posted.


Turn setting on for both bots

Posting a powershell file results in silent bots (verified by logging).
Posting a python file results in a review posted.





Revision 2 is currently untested as I ran in to some issues with trying to manage the settings entries in the database through django. I may need some assistance if you'd like me to test it before submission *