Add triggers and alarms for Neutron agents

This patch adds monitoring of the neutron-data cluster in case Neutron
uses OVS instead of OpenContrail.
It adds new triggers for l3, metadata and openvswitch agents to
detect whether one agent is down, only 2 agents are still up or all are
down. It also adds a new AFD based on these triggers and its
corresponding GSE on the aggregator.

Change-Id: I71a4f87b66d4ef1c44efd394c2369aceed90098e
1 file changed