glusterd: delete "volume-name" from dict before processing the next option

Change-Id: Ib78963c1f43a66dab50b443742979c7c4e4cbc23
BUG: 958790
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/4940
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>