Adoption of the Neutron Classifier in Neutron QoS for neutron

Integrate Neutron Classifier with QoS DSCP rules

API for l2 agent extensions (+ovs flow management) for neutron

L2 agent extensions were introduced in Liberty. Currently they don't have any way to influence agents that they run inside. For example, there is no way they can set flows for OVS bridges, create new tables, add patch ports, etc. Multiple subprojects (SFC, BGP-VPN) expressed the need for such mechanism that would a...