Add Link to "forgotten password?" to sessions form
Create password_resets_controller

Add edit, create and update to it. (And private methods, although they are not yet working..)
Create password_resets routes
Add form to enter email to reset password
Create password_resets_controller pt. 2
Add new columns to users table

We added "password_reset_token" and "password_reset_sent_at". The token will be sent in an email for the password reset. It has to expire after 2 hours, which is why we need the time.
Add send_password_reset method to User model
Create User mailer with password_reset method
Edit text for reset password mail.
Change settings to enable URLs in mailer
Add view for password update