Bug #1195312 Enable quantum security groups

For quantum security groups, we need to switch to the libvirt_vif
LibvirtHybridOVSBridgeDriver and set the firewall_driver in the
ovs_quantum_plugin
Expose libvirt_vif knob at top level manifest
Merge pull request #92 from rickerc/fix_security_groups

Bug #1195312 Enable quantum security groups