Add booklet expiration dates

[wolfskaempf]

The data contained in booklets is usually not needed for longer than 30 days, but contains a variety of personal information. Data which isn't there can't be hacked, so to enhance the security and lessen the impact of a potential security incident, booklets should automatically be marked for deletion after 30 days. In case a user does need their booklet for longer, it should be possible to reset the timer.