gerrit-wm: pywikibot/* events to #pywikipediabot

I based this off of change I5dc98959b3e06728838239e57a56e4c27f49092d
(commit f959cea0) which did the same for twn/i18n commits.

I also added a couple unit tests.

Change-Id: Ia4d47e1a102ecc04aa2968719a7c01eb7af03cfc
Merge "gerrit-wm: pywikibot/* events to #pywikipediabot" into production