MB-100: reuse open_latest_store() helper
MB-100: reuse open_latest_store() helper

Change-Id: I4b46da08f602be96b8be5a62a98670d48c2650c2
Reviewed-on: http://review.couchbase.org/18853
Reviewed-by: Ronnie Sun <06648be64f8fbc529d817d157ec32d385ea42f22@couchbase.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

membase/membase-cli,couchbase/couchbase-cli,couchbaselabs/couchbase-cli,membase/membase-cli,couchbaselabs/couchbase-cli,couchbase/couchbase-cli,couchbaselabs/couchbase-cli,membase/membase-cli