Allow inferior engines to include engine-specific data.
Allow inferior engines to include engine-specific data.

Change-Id: Ic9600095a16c14074b34918c98bc01bd0f1e7275
Reviewed-on: http://review.northscale.com/1468
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

couchbase/bucket_engine,couchbase/bucket_engine,membase/bucket_engine,couchbase/bucket_engine,membase/bucket_engine,couchbase/bucket_engine,membase/bucket_engine,membase/bucket_engine