Update DB-enabling scripts and utils.appliance

Added v2_key copying from primary to secondary appliance when enabling external DB in 5.3
Fixed region setup when enabling internal DB in 5.3 (was forced to 1)
Added `loosen_pgssl` method and added it as part of `configure` (it is ran after DB setup; does nothing in versions below 5.3)
Added `is_db_ready` and `wait_for_db` methods (thanks psav)