Steps to reproduce:
1. Create a new scheduled event
2. Create a new user which doesn't have ROLE_ADMIN
3. Give the new user write access to the scheduled event
4. Login as the new user
5. Try to Actions -> Edit scheduled events
Actual Results: Browser's console show 403 for event/scheduling.json and event's scheduling data is not displayed correctly.
Expected Results: Edit scheduling events works as with ROLE_ADMIN