Remove ep-engine includes

Everything we need is right inside memcached.

Change-Id: Ifba333f6253d90a50cced7d4114c97ff8df42456
Reviewed-on: http://review.couchbase.org/43790
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>