Show age when editing assignments

[timreyn]

During New England Champs, we had some issues with younger runners who were too quiet to be effective runners. It would be very helpful to see the competitor's age while assigning jobs, so that I can prefer assigning older (say, 14+) competitors to be runners.

Age is of course not the only factor when assigning jobs, but it's a very relevant data point.

[coder13]

Quickly did this!