Use configured DB passwords instead of hard coded
Use configured DB passwords instead of hard coded

- To override the default master db, username and password, specify one
or more of:
  DRIFT_POSTGRES_MASTER_DB
  DRIFT_POSTGRES_MASTER_USE
  DRIFT_POSTGRES_MASTER_PASSWORD
- Provisioning scripts will also use the specified user and password in
the tier or tenant config instead of the old hard coded values.
- Caveat: There's no support for changing the password during an ugprade.

dgnorth/drift,dgnorth/drift,dgnorth/drift