Switch team invitations to use alerts
Delete superseded team invitations
Delete left-over rake tasks
Ditch the notifications STI
Add migration to remove STI in the db
Delete the SubmissionNotification.

The migration had to be run in production before the class could be
removed.
Delete leftover fields on notification
Correct sum-of-multiples blurb.

The tests are for "up to but not including", not "up to and including".
ocr-numbers.md: fix code indentation
Reorder controller endpoints

The user controller has some catch-all endpoints that get in the way of
other endpoints.
Merge pull request #1328 from henrik/patch-7

ocr-numbers.md: fix code indentation
Merge pull request #1327 from henrik/patch-6

Correct sum-of-multiples blurb.
Temporarily implement polymorphic association

The Notifications in the v1.0 design are going to be based on the user
exercise, not on the individual submissions. In order to support both
the beta and the v1.0 designs in production simultaneously, I've decided
to use a polymorphic association and a duplication hack that keeps the
related notifications in sync.

This will be removed when the beta application is retired.
Implement duplication hack for notifications
daily email message. sends user unread notifications and some pending submissions that need nitpicks
Rename Daily -> Notification message. Make email multipart (html/plain text). Only send email if user has notifications
do not send email if in CI. remove extra line in email
update notification message to work with change in notofications. update spec