P0 xdcr

Change-Id: I02591a1fcba963509860ba4450f37f32ae8b0dc4
Reviewed-on: http://review.couchbase.org/26219
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: Ketaki Gangal <ketakigangal@gmail.com>