engine: BLL Command to Stop Reblance Gluster Volume task

BLL Command to Stop Reblance Gluster Volume task.
It will clear the task details in the Gluster Volume also
set the job status to Aborted.

Change-Id: I0e7cf0eb4de160dc309f2699ba0e224f48dd1f49
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>