Implement 'minimum LCB version' for tests

Change-Id: Iba9bdbf481c5aab1124168b2b5fa54c4ede4d550
Reviewed-on: http://review.couchbase.org/27487
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>