glusterd: Made gsync set use synctask framework

Change-Id: I409fa5a9f55434ece47a8a51d4812d3eca42d269
BUG: 852147
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/4473
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>