Add base CourseAlert models
Make CourseAlert an ABC; add methods to send and delete
Add tests and fixtures for BaseCourseAlert
Add GcmCourseAlert subclass to send out Android push notifications
Send push notifications automatically on each sections update
Add POST /api/v1/alerts/course/gcm endpoint and tests
Add DELETE /alerts/course/gcm/<string:alert_id> endpoint and test
Oops, fix bug with BaseCourseAlert.delete_expired

... deleting items with expiry dates in the future instead of in the past. Also
fix terrible test that did not catch this case. Double oops! Thanks for the
catch @mduan!!
Merge pull request #140 from UWFlow/david-push-notifications

Add support for push notifications to our Android app
Display bell icon next to full sections
Extract iteration out of template and into JS
Extract TermView to remove more template iteration
Add prof linkification on TermView
Sort terms, oldest to newest in SectionCollectionView
Move all collection iteration into SectionCollectionView
Refactoring - extract rendering methods
Refactoring - stylistic cleanup
Move data gathering out of template
Add ajax call and change button cursor to pointer
Add EmailCourseAlert class and API endpoint