dht: Set status to FAILED when rebalance stops due to brick going down

Change-Id: I98da41342127b1690d887a5bc025e4c9dd504894
BUG: 1038452
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/6435
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Shishir Gowda <gowda.shishir@gmail.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>