Fully quality ipython path

Change-Id: I86c14ac3b6d2dba7dfa6ddf72da7f5672f43cc88
zuul: support cloning from a different branch

We might want to maintain a fork of Zuul in labs.  For that purpose the
Zuul module learned the `git_branch` parameter (default: 'master') that
would let us specifiy from which branch to clone Zuul.

Change-Id: I69c0c5199797c56f97bc84e64489b90a2b61451f
Merge "Fully quality ipython path" into production