Scheduler (or admin) can edit the schedule

[bitemyapp]

Given a slot structure defined by #22:

• Queue of talks not assigned a track+time slot.

• Scheduler can assign a talk to a start time and a track. Tracks are really just locations/rooms. End time is abstract type length defined. Might also be tagging at this time, cf. #23

• Warn on overlap.

We might be doing a dirty/SSR implementation of this if we can't find a frontend person to make something slick.