New user activation

[Briehan Lombaard]

Implement the registration activation flow detailed on the project wiki.

The process should roughly be:

• when a new user registers, their account is inactive at first
• a message is displayed telling them that an activation email has been sent to their email address
• send out an email with an activation link
• the user clicks the link which then activates their account and redirects them to the login form
• they can log in using the credentials they provided at registration

[Briehan Lombaard]

Fixed in 6d71d4c