Allow users to request a "delete info link" with their email

[fallen]

1. they enter their email
2. database is searched for signatures matching this email (hashed and not hashed, confirmed or not)
3. an email is sent with a one-time-link
4. link shows page with all those informations, allowing user to select each (or all) they want to delete

=> allow to delete personnal information, but with no account