glusterd: Made volume-quota use synctask framework.

Change-Id: I4c275253144ed3ac11a701a56dd1116c002471ba
BUG: 852147
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/4495
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>