Got rid of required default initialization.
Got rid of required default initialization.

Engines are only loaded when requested, and we can theoretically place
a different engine name in for each request.

Change-Id: I3a2bf2772455f7fcb3e9774757097a89069465d5
Reviewed-on: http://review.northscale.com/1486
Reviewed-by: Sean Lynch <9c3328a4a1f4f8f5c18b2d5b9057163c49b93ff3@literati.org>
Tested-by: Sean Lynch <9c3328a4a1f4f8f5c18b2d5b9057163c49b93ff3@literati.org>

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