rcopenstack-neutron-ovs-cleanup required before reboot

[tpatzig]

On our network nodes an rcopenstack-neutron-ovs-cleanupwas required prior to the reboot, to have network working, after the node starts, otherwise it hung up in crowbar_join. @seife please provide more details from the maintenance, if you have

[vuntz]

I think this is a duplicate of https://github.com/sap-oc/crowbar-core/issues/24