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)

__How to test:__
```
from utils import appliance, conf
appdata = conf.cfme_data['appliance_provisioning']['appliance_set']
apps = appliance.provision_appliance_set(appdata, 'test_pr1160')
```
This should provision 2 appliances (1 master, 1 slave) - you need to have the appliance versions set in the yaml + you need to have template names assigned to those versions there as well.