'Blank Form' championship setup

[rickselby]

Ideally this would be very similar to the AC setup, but needs to allow manual entry.

Perhaps merge everything? Keep the DiRT stuff as that's completely different, but rename 'AC' to 'Races' or something, and allow different ways of entering the data, but it'll all be shown in the same way, summed, etc.

[rickselby]

• [x] ac_guid should be steam_id
• [x] Remember to add in races_categories and generate menus (etc) from that

[rickselby]

Still to do: allow manual entry....