Adds openvswitch networking prior to packstack install

Adds openvswitch networking to the packstack environment
prior to the packstack install. We are specically not changing eth0.
Bridge can be setup on eth1 or eth2 depending on the topology settings.
Instances launched will have a floating ip on the bridged network.

Corresponding khaleesi-settings change #32121

* update to get setup_openstack_elements order, ensure br-ex is up
* update tempest openstack-elements w/ ksgen style settings

Change-Id: Ib9a529c7abe4f30e37d6c700adefe593c34ddbec