Stop all engines during shutdown
Stop all engines during shutdown

Change-Id: I12cee9d89742437114c687196eaffa1813fb04f0
Reviewed-on: http://review.membase.org/5228
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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