cluster/dht: synchronize rename and file-migration

Change-Id: I4f243c946f76d440680b651235f925e3d0ebf0fd
BUG: 1138395
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on-master: http://review.gluster.org/8523
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/8613