Only allow one session submission per person per event

Current problem

There's a problem in the community whereby some people flood events with three+ sessions per event, even for small events with 20-30 session slots.

Suggestion

Change the system so that by default the system shouldn't allow any more than one session submission per event.

UI changes

Provide a setting that allows controlling the maximum number of session submissions a single person could create, with a default of 1.