Add drain rate, remove bixdcr(temp)

Change-Id: I1cce0028e6357c5fa0f9c6dbc4ff52cc0e8f83d1
Reviewed-on: http://review.couchbase.org/25820
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: Ketaki Gangal <ketakigangal@gmail.com>