mgmt/glusterd: Set task op at the time of task-id set

Problem:
If a remove-brick start is executed on m1 with brick from m2
on local subvolume no rebalance process is launched. Because of
this volinfo->rebal.op is not set. This leads to volume status
failures.

Fix:
Set rebal.op even when the reblance process is not started.

Change-Id: I71c7e6f09353be14c1e8edca3c8685ebfdf226d6
BUG: 964059
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/5030
Reviewed-by: Kaushal M <kaushal@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>