packaging: setup: check existing VMs running

Check if there is already any VM reported as running
by VDSM and fail if it exists.

Change-Id: Iae7b88d5c56bd76b87cfcdef29e629a3a30b6491
Bug-Url: https://bugzilla.redhat.com/1034726
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>