"clear the shopping list" is not clearing the database

[hanna-z]

I'm not sure if it is worth a new issue, but I try:

As mentioned in #190 at the moment "clear the shopping list" is clearing the order and the persons. But is not clearing the database. So if you enter your data and clear the shopping list your name and e-mail address is still in the database and you can't start over with the same e-mail address. (As it already exists).

The database should be cleared as well as it is when you delete the person separately by using the "trash bin sign" on the same page near to the name or on the "personal details" page