Enable xdcr on Sanity tests

Change-Id: Ibcbcc983f6e05fe349eca43e86d7270227d51458
Reviewed-on: http://review.couchbase.org/25823
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: Ketaki Gangal <ketakigangal@gmail.com>