Minor cleanup
Create separate alerts mode for aggregator
Send email as HTML
Add toastr notification for successful alert creation
Add toastr notification on alert add failure
Expose alerts for given user through V1 API
Display different icon for sections with alerts
Variable renaming
Extract AJAX call into Alert Backbone model
Add client-side code to delete alerts
Add email course alert deletion endpoint
Handle case where email alert is not found
Properly unset alert on successful destroy