token: Protect against null tokens.
front: Remove duplicate import.

has_opted_out is defined in mail_queue, but is also exported from
models/__init__.py
emailer: Remove extraneous imports.
emailer: Remove extraneous whitespace.
mail_queue: Remove extraneous whitespace.
mail_queue: Remove extraneous imports.
Add methods to send a password change notification.
api: Send notifications of password changes.