Service monitor changes - Phase 1

1. Configuration from rabbitmq (runtime) and cassandra(at startup)
2. Build local db and dependency graph
3. Invoke Loadbalancer driver from service monitor

TODO:
1. build dependency for service chain related objects.
2. Move service chain code to use the local DB instead of vnc_api calls.
3. New infra is disabled. Need to enable it after testing

Change-Id: I4f51333e25289e1a9f6f08b7eea760132f88b0da
Merge "Service monitor changes - Phase 1"