Use static Loggers

A few classes were using loggers named after other classes; I'm assuming
these were typos from copy-pasting.
Replace System.out.println with logger.log(Level.INFO
Add option to disable ssl verification for ghprb hook url
Treat "synchronize" pr actions the same as "opened" and "reopened"
Fake pr synch events for issue comments on open PR's
Overly verbose logging to figure out what's going on

INFO everything isn't sustainable, but I don't think all the quirks have
been ironed out yet so I'm erring on the side of verbosity
Live dangerously

I've only managed to get this plugin to work with fixes to
github-api that are as yet unmerged:
- https://github.com/kohsuke/github-api/pull/36
- https://github.com/kohsuke/github-api/pull/37
Try to hack around NPE on PR syncrhonize