Allow testers to sign up

[jelly]

Currently testers have to mail someone to get an test account, to reduce the manual workflow. The flow would be:

• Sign up with a username, firstname, lastname, email, password
• User receives an email with a unique url
• User clicks the email, archweb sets user as "accepted"
• Admin verifies the account in a queue and approves
• User receives an email with a short introduction to testing.

The hash for the unique url could be something like: hash = sha256(str(time()) + user.email).hexdigest()

[jelly]

@grazzolini please review/expand if needed.

[grazzolini]

The flow seems fine by me, it is what we have discussed. The authentication flow is easy enough, but we'll have to decide how the moderation is going to take place. Perhaps, create a new permission, so not only django admins can moderate, and send an email to all users that have that permission.

[jelly]

This will most likely get superseeded by OIDC support, as we can simply assign folks to the Tester role.