We add a few templates for django-confirmation. We define a
"PreregistrationForm" which is validated by accounts_home, which then
generates a confirmation object and emails the user. This required creating
a new table for a PreregistrationUser with an email and status (confirmed)
field.
The register function now no longer accepts a "email" field in the form
and deals only with confirmation IDs to determine the email used to sign
up a user.
(imported from commit 4fcde04530aa7ad4de84579668daee7290b424ac)