bug #1039400
- make quantumv2/api.py fetch actual DHCP server address, which
is needed by firewall layer (otherwise, the gateway IP is
incorrectly used and all DHCP traffic is dropped).
- add missing call from quantumv2/api.py to the security
groups API when a VM is allocated/deallocated.
- Add a vif-driver that is a hybrid of the existing Open vswitch +
linux bridge drivers, which allows OVS quantum plugins to
be compatible with iptables based filtering, in particular, nova
security groups.
- Also clean-up some docstrings in virt/libvirt/vif.py
Change-Id: I7cf5cf09583202a12785b616d18db3ee4bbffee0