* Fix type mismatches in coursewaqre
* Fix type mismatch in credit migrations
* Fix type mismatch in status migrations
* Fix type mismatch in user_api migrations
* Review Fixes
Django 2.0 will make this field required for `ForeignKey` and `OneToOneFields`.
In previous versions the option defaulted to `models.CASCADE` when not
specified. This change should make the deprecation warnings in the current
Django version go away.
The migrations where also modified, but the changes should not cause a change in
the database schema since `models.CASCADE` was already the old default.
LEARNER-1894
This commit adds in course messaging for three use cases. First,
when the user is not signed in, the user is shown a message that
provides a link to sign in or register. If the user is signed in
but not enrolled, they are given a link to do so. If the user is
enrolled but the course has not yet started, they are shown a
message explaining when the course starts and shown a link (not
yet enabled) to add a reminder to their calendar.
The implementation defines a base message class and extends it
for the course home messages as well as the previously implemented
page level messages.
