corosync: Fix search for authkey when there are multiple clusters
Correctly set corosync cluster name in crowbar-pacemaker wrapper

The name ends up in corosync.conf and is supposed to be unique
for each cluster.

Right now, it's only used to automatically generate a multicast address
when no multicast address is specified (not the case here), but this
could potentially be used for other things later on.
Merge pull request #79 from vuntz/fix-multi-cluster

Fix search for authkey when there are multiple clusters