glusterd: Use client-op-versions during "volume set"

The supported op-versions of the client and the name of the requested volume,
are saved during server_getspec(). These are used during the staging of volume
set. If the option being set is not supported by any of the clients which
currently have the volume mounted, then set will fail.

Change-Id: I4e6b60b274d5200508762dc0204cfa848a6c0aa4
BUG: 907311
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/4424
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>