Disable VIPs before stopping cluster during version upgrade

Disable VIPs before stopping cluster during version upgrade

If "pcs cluster stop --all" is executed on a controller that
happens to have a VIP on the internal network, pcs may use the
VIP as the source address for communication with another cluster
node.  When pacemaker is stopped this VIP goes away, and pcs never
receives a response from the other node.  This causes pcs to hang
indefinitely; eventually the upgrade times out and fails.

Disabling the VIPs before stopping the cluster avoids this
situation.

Change-Id: I6bc59120211af28456018640033ce3763c373bbb
Closes-Bug: 1577570