hypervisor: ensure RBD can't be enabled on RHEL

RHEL does not support RBD backend for VMs storage.
We need to ensure that nova will never be configured with RBD
parameters, even if has_ceph is true on Red Hat hypervisor nodes.

Also add more unit tests.
CHANGELOG: Notes for 1.2.0 release
lb: fix lint
telemetry: include notification agent in server class

- Include Ceilometer Notification Agent in cloud::telemetry class
- Add tests
bring Heat APis multi workkers
neutron: fix report_interval

report_interval should be configure on all neutron agents.
neutron: use new model for enabling security group API