Fix nsx plugin deploy on Centos

Add neutron-ml2 package for non-obvious neutron dependency (neutron
start fail without it)
Add notify "neutron-db-sync" resource, because neutron-server package
in our module installed as a dependency

Change-Id: I1ae8c05c54ddf2d6b175eb1a13ecfa70a569a0e3
closes-bug: #1392244
Merge "Fix nsx plugin deploy on Centos"