CGP107: Course Calendar Save the date

[lebaz20]

• [x] Add A button "Calendar Alert" beside each course event to send a mail with a link to Add event to user's personal calendar
• [x] Add A button "Periodic Notifications" beside each course event to send a mail notifying user with course starting date with the option to stop periodic notifications after subscription

[lebaz20]

• Calendar alert
  • [x] calendar alert action
  • [x] use addToCalendar library
  • [x] update calendar privileges to set start and end dates and time zone
  • [x] email course event calendar to user
  • [x] ACL for calendar alert
• Periodic Notifications
  • [x] Periodic Notifications subscribe/ unsubscribe actions
  • [x] ACL for periodic notifications subscribe/ unsubscribe actions
  • [x] Add course event subscription entity
  • [x] Add command to send notifications every x days
  • [x] email course event periodic notification to user
  • [x] Load subscribe/ unsubscribe forms in calendar page

[babanesma]

• Calendar alert
  • use bower instead to load the library