CBD-926: Memcached should use the 2.0 branch

Change-Id: I25ddc58d14c82e6f990248e7a1dd811ef07d93af
Reviewed-on: http://review.couchbase.org/25477
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Philip Labee <philip@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>