Add a staged rota generation process

[TechWilk]

It's difficult to create a rota, so let's make it easier by working to a standardised process.

One possible process:

1. Add dates "we need to create a rota for these events/dates"
2. Gather more information
   • Request availability "who can do which dates"
   • Add event details "what does each event involve / what's happening"
3. Assign people to events
4. Distribute initial rota
5. Any last minute swaps
6. Reminders x-days before event
7. Rota about to run out reminder (x-days before final event)
8. Return to step 1).

Need to consider groups possibly working to a different timescale for rota generation.

• perhaps the process should be capable of running 'group specific' and also 'site wide'