Add course alert deletion

Add email course alert deletion endpoint
Handle case where email alert is not found
Properly unset alert on successful destroy
Delete expired email alerts in aggregator
Cleanup

Capitalize all letters of course id in email

Minor cleanup
Extract the AlertView

Clean up and extract _renderAlertIcon
Accept application/json at endpoint
Use built-in Backbone destroy method
Add has_email_alerts property to User model
Add tooltips to alert buttons
Add course alert notification to profile page
Add get_email_alerts property to User model
Add Alerts section to profile page

Minor wording changes
Take care of toJSON BSON business
Fix Alerts when not logged in