tests:Adding remove-brick test to volume.t

Change-Id: Ibef0c151ef6518136cd5f4c39ec5e89f06ff4133
BUG: 764966
Signed-off-by: Lalatendu Mohanty <lmohanty@redhat.com>
Reviewed-on: http://review.gluster.org/4650
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>