Plug Vif into Midonet using Neutron port binding

Currently Midokura uses its own script (mm-ctl) to bind ports. However, support
for using this script is left out of the nova and neutron projects. This causes
confusion and makes deployments unnecessarily complicated for customers using
Havana. This fix is to change nova to properly use mm-ctl. Corresponding
changes will be submitted to devstack and neutron.

Change-Id: I7c9edded5ab6fe19b63e54cd6905d9242e4a90cc
Closes-Bug: 1235132
Merge "Plug Vif into Midonet using Neutron port binding"