vdsm.spec: fence-agents-all

fence-agents package in version 4 replaced the package name
to fence-agents-all. This patch will adapt vdsm spec to this change.

Change-Id: Ia7933fd043e535b568ce368e8e61f44e330b25ae
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/13729
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>