Constants Updates

Organized the constants file.
Removing AssignmentTypes Controller

AssignmentTypes should only be dealt with in the admin panel where new ones can be created or destroyed. Professors will only specify an assignment type for a given assignment, but there is no page or controller that should be dedicated for an AssignmentType within the main application.
Oops

Forgot to delete this file with the previous commit
Authorized Course pages

The course pages are now all authorized with cancan. I've also removed the ability to create, edit or delete any courses through the main webpage via the courses_controller since this should be done in Active Admin. An unauthorized message will still be shown to those who are not admins who try to access pages such as courses/new or courses/1/edit, but admins who do have access will just be redirected to the main courses page.

I also an observer1 account:

observer1@whiteboard.com
password
Removing unused files

We won't be using any of these files with our application whether it's because creation and editing will be in Active Admin, or the page will consist of AJAX calls that won't require the additional pages.
Cancan Authorization Updates