Update GBP projects for tarballs, pypi & gerritbot

Updates to the Group Based Policy stackforge projects to:

* Generate tarballs on tag events

* Add publish to pypi jobs

* Configure gerritbot

Change-Id: Id36fb3261ef3b73a1a770e24662fe2da318724a1
Merge "Update GBP projects for tarballs, pypi & gerritbot"