add email verification to registration flow

[cranaweeraproject]

We need to add email verification to the registration.

current flow:

1. user submits regisration form
2. user sees registration confirmation page

should be:

1. user submits registration form
2. users sees an information page that we send a mail 2a. at the same time we send a mail to the user with a verification link
3. user clicks on the verification link
4. user sees registration confirmation page

Texts still to be defined when we want to do it

[jacksbox]

Please add this issue in the backend repo. https://github.com/bcye/lokalshoppen

closed