Add better export possibility
Description
We need to be able to deliver letters to "not-anymore-certified-people". In order to achieve this, we have to export the listing, as it is the only maintained source we have.
The following problems were discovered while trying to do an export:
- When listing all records of tx_certifications_domain_model_user in the single table view, the field "certificates" always states "10-09-11". I'm not sure if I get the value wrong, but that seems off
- When exporting tx_certifications_domain_model_certificate, almost all required data is available, but the user data (name, address, etc) is missing.
- Exporting all tables manually and trying to join them in e.g. excel fails as primary keys are not available fields for exporting in the single table view.