bucket_engine is dead, long live memcached
bucket_engine is dead, long live memcached

bucket_engine is removed in Watson, and memcached is now
multi-bucket aware. As part of the merging the engine
parameter is ignored from memcached.

Change-Id: I05dae0525a6766434d14d527a9049ce376473626
Reviewed-on: http://review.couchbase.org/52428
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server