updated quickstack/manifests/pacemaker/neutron.pp to include

neutron-agents-pre group, which handles the cleanup of agent
resources (qrouter, qdhcp, etc..) when those are migrated to
different hosts.

It's done to match ocf changes around that line.

https://github.com/fabbione/rhos-ha-deploy/blob/master/rhos5-rhel7/mrgcloud-setup/RHOS-RHEL-HA-how-to-mrgcloud-rhos5-on-rhel7-neutron-n-latest.txt#L104

I'm not 100% sure the if our 'clone' at lines 131 and 136 is equivalent to the clone in line L104.