Change some repos from xenial to bionic
Change some repos from xenial to bionic

At the time of bumping Ubuntu images to bionic, some repos did not have
bionic versions - so xenial repos were used.
Most of the repos - apart odl now have a bionic tree - so this patch
enables them.

Change-Id: Id3c67fad507adc7b9f200eced74ecba8fadf70e6

openstack/kolla,openstack/kolla,stackforge/kolla,stackforge/kolla,rahulunair/kolla,rahulunair/kolla,stackforge/kolla