Add test validating migration from iptables_hybrid firewall driver to
openvswitch. The test creates simple environment with a single node then
spawns two vms, each has its own security group. Then firewall is
switched and OVS agent is restarted. Connectivity is then validated
again, security groups are removed, tested no traffic is allowed and
then security groups are added back to make sure new firewall driver
works with updates.
Change-Id: Idef80c76c1b82be9f1007f17ea661c9ccdc2b1ae