JSON Backup

[mic-e]

Group members should be allowed to download all group data as a JSON dump. Likewise, users should be able to create a new group by uploading a JSON dump.

This serves a multitude of purposes:

• Backup to prevent loss of data if this hosted instance of the Abrechnung goes offline.
• Trust anchor for users who fear manipulation of the online data
• Users can download the group dump and play with it in a local sandbox
• Users can download the group dump and analyze it with their own script to generate metrics or perform whatever analysis that is not possible via the web interface
• Users can use the JSON upload feature to bulk-import data from other systems
• If a user loses write access to a group they can create their own 'fork' easily

Not sure about binary attachments, they could be gotten as a zip file or whatever. We should under no circumstances allow replacing group data with an offline backup, this would completely destroy the trustworthiness of group data.