CBQE-981: wait_for_memcached before getMeta

Change-Id: Ia54d3aaa755ae97784f9f8afb002bb8f3d4c27e0
Reviewed-on: http://review.couchbase.org/24154
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>