Set router-api vhost on development VM
Set router-api vhost on development VM

This was omitted in 9faacc2b. We must set a value as this parameter is
mandatory.

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