Prefix all tests with memcached-

Change-Id: Ie781e7420ff3af4479cfdc913aa1b8c3c04c12bb
Reviewed-on: http://review.couchbase.org/32715
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>