assign coordinators to events in groups

Instead of assigning coordinators one by one to an event, set up functionality to have a group of coordinators assigned to an event.

Case Application:  We are a non profit PB club with no staff and we rent our courts.  We have a host at each event who is responsible for checking in registered players.  There are often changes in the hosts and it is difficult to make last minute changes, so we would like a group of hosts to have the ability to check in players.