Make a tests configurable in terms of underlying postgres

[Dmitry-Erokhin]

As far as pg container is running externally from test, some degree of flexibility should be added.

• Major postgres setting should be parametrised via build script parmetrs:
  -- hostname (optional)
  -- database
  -- user
  -- password
• All the settings should be passed into the tests (envvars?) to enable it connect to the databse