mgmt/glusterd: return failure when server quorum is not met

Change-Id: I0a7df141d01cf70da5aac9658b2a5a19f660dd3b
BUG: 1101561
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/7894
Reviewed-by: Sachin Pandit <spandit@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>