Install openstack-neutron-ml2

openstack-neutron-ml2 is the package we should actually be installing
here.  openstack-neutron-ml2 requires openstack-neutron, so technically
we don't need to list openstack-neutron at all, but I left it in as it's
more visually expicity of what's happening.

Change-Id: Ia1b81cfa658b352ec7799fd67dfa1dd9d14463cd
Merge "Install openstack-neutron-ml2"