Upgraded gunicorn to 19.1

* Upgraded gunicorn to 19.1 to gain timezones in logs
* Altered docker-registry logging to include timezone
* Altered documentation to more closely reflect implementation
  (-w and --max-requests flags as per use in run.py)
* Removed unecessary documentation from wsgi.py
* Removed deprecated --debug flag
  (http://docs.gunicorn.org/en/19.0/news.html#core)