Revert "Use git://git.openstack.org as GIT_BASE like devstack master"

This reverts commit 11b98fe126cba55712509609cf54f4379fcd3fde.
I'm not entirely sure why, but moving away from the github mirrors was causing
our devstack fork to break.
Merge pull request #19 from ryanpetrello/akanda/havana.rc

Revert "Use git://git.openstack.org as GIT_BASE like devstack master"