Adjust scripts to upgrade to Cloud 4

* Handle possible absence of barclamp-pacemaker on a non-HA setup
* Write helper-neutron-migration to do the database migrations for neutron
* Rename reboot-node to prepare-and-reboot-nodes and extend it
Hrm, this is too fragile (especially the grep). We can't parse json that way.

What about doing this:
```
role=$2
nodes_with_role=$(knife search node "roles:$role" -a name | grep ^name: | cut -d : -f 2)
```
and then make sure to only keep the nodes that are in `$allocated_nodes`?