Count cancelled and non-cancelled seats seperately on /elections/<id>

[chris48s]

At the moment, the "Seats Up" total includes cancelled seats. On a page like this one, this is unhelpful because the total includes several hundred seats where no election is actually taking place.

That said, excluding them completely would be odd on a page like this because you'd say "Seats Up: 0"

I think the solution is to present total/cancelled/non-cancelled as 3 different totals for clarity

[pmk01]

Could we differentiate between cancellations? Useful to know how many have been won uncontested and how many will be rescheduled due to death or undercontestation.