features/quota: Fix dict leak

Change-Id: Id4542d1629175cce5fec5ab8f9a5899eec48e2eb
BUG: 1110777
Signed-off-by: Varun Shastry <vshastry@redhat.com>
Reviewed-on: http://review.gluster.org/8132
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>