Disable stonith temporarily during upgrades

Disable stonith temporarily during upgrades

It is best if we disable stonith if a cluster has it configured and on,
before we call "pcs cluster stop --all", because should a service fail
to stop for whatever reason, pacemaker will fence the node where it
happened. This is something that we unlikely want during an upgrade as
it will make things worse.

Once the cluster is stopped we can reenable stonith (if it was enabled
to start with) in the CIB while the cluster is shut down.

Closes-Bug: #1596065

Change-Id: I38dcacfabc44539aab1f7da85168fe44a1b43a51