Re-enable CKAN in staging
Re-enable CKAN in staging

The issue with postgres connections which we saw previously
may have been resolved by the use of pgbouncer, so we're
re-enabling in staging only to see if the problem persists.

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