Epic: Friends-Experience

[ski7777]

Angels have friends and the like them. I want to help angels to find their friends in shifts or even work together as dream teams.

Steps needed to implement this as roughly discussed as 38C3 with @MyIgel:

• [ ] Friendship
  • [ ] users can request friendship with other user
  • [ ] users can accept incoming friendship request
  • [ ] users can reject incoming friendship request
  • [ ] users can abort outgoing friendship request
  • [ ] users can block other users
• [ ] Friend shifts
  • [ ] see current/upcoming/last shift of befriended person
  • [ ] see timetable for befriended person
  • [ ] filter for shifts with friends registered for shift
  • [ ] notify users when friends register for a shift and the users is eligible for the shift and has no collisions