Make DNF handling clearer

[natebazar]

The DNF handling was really unclear to me and made handling it a bit of a pain. It also made it somewhat difficult to understand until I emailed Jeff a bit. To fix it, I made DNF times (>9.9) be displayed as 'DNF' to make it clearer for audiences. Also added a note to the 'Manual Results' page to indicate that 9.999 will result in a DNF time.

Manual Results

Race Dashboard

Race Standings

Note: This left the original time so the averages work out when people try to guess what they should have since the 9.999 gets averaged in.

Results by Racer

Racers on Deck

Now Racing Kiosk

Now Racing Columnar Kiosk