Move neutron agents out of Pacemaker to systemd control plane

The neutron agents in Fuel ref arch have been historically running under a Pacemaker CP via custom OCF RA.
Times have changed, now the agents are running as clones at all nodes, without any coordination / shared state across nodes.
Also, MOS is going to implement systemd based init scripts for Openstack services once switched to Ubuntu Xenial.

This allows Fuel to remove the neutron agents from a Pacemaker OCF control plane, as there is just no need for additional features Pacemaker provides.
Instead, run those as ordinary systemd service units with respawn capabilities.