Initialize on every page that has a context_course set

textbook.js is apparently being loaded on every page, so I just made sure that
Backbone Associations was also loaded on every page to be sure that the dependency
was always being met.

http://epeli.github.io/underscore.string/

Models are extraneous for something as temporary as a notifaction -- this change
moves all the configuration into the views, and removes the models entirely.

Also, a SystemFeedback model no longer has a `type`, it has an `intent`. This is
because SystemFeedback views have `type`, as well, and this prevents a naming
collision.

studio - revises copy of server error notification to include a default message and removes associated actions from notifications

Model shouldn't know about things like close buttons, visibility, and so on

To create handy WarningMessage, ErrorMessage, and ConfirmationMessage classes

And delete `CMS.ServerError`

Not that it really matters, since the changes are invisible :)

Matching docstring in feedback.js models