Replace github with git.openstack.org
Replace github with git.openstack.org

The git.openstack.org has been the recommended git repo for OpenStack
projects.

Change-Id: Ibc973efec60a5f1c9c7a584460b4c00e2d4f7b2e

openstack/mistral-dashboard,openstack/mistral-dashboard,openstack/mistral-dashboard