Fix broken download links on heroku
Fix broken download links on heroku

The path call works with filesystems, but not where S3 buckets are
concerned.  This is a quick-fix for that for now.

ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments