Inform a client if Quantum provides port filtering feature

Part of blueprint vif-plugging-improvements

Quantum and Nova have duplicated functionality of packet filtering
such as security groups and anti spoofing filters.
By passing information whether Quantum supports the port filtering feature,
Nova VIF driver can skip its own packet filtering setup.

It is based on Daniel's advise in https://review.openstack.org/#/c/19436/

Change-Id: Ifd260cb61aa3990251510a4a3fe15454d8d584df