Tests: util to check if replace brick completed

Change-Id: I7748395395454765a35e34611d11f58dd4ef3efb
BUG: 857549
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/4450
Reviewed-by: Anand Avati <avati@redhat.com>
Tested-by: Anand Avati <avati@redhat.com>