PostgreSQL: Allow auth from API network
PostgreSQL: Allow auth from API network

Allow authentication to occur from the API network using a passphrase. This
is used by Stagecraft as it lives on the API machines.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet