Reports could also talk about running times

[Janiczek]

I feel like this is a blind spot of the current report format: it doesn't talk about how many seconds elapsed at all.

In my implementation (https://github.com/jlink/shrinking-challenge/pull/34) the lengthList challenge can easily ran for 10 minutes because of some O(n^2) behaviour for long lists. Yet just by reading the report you could think it's actually pretty OK.

[jlink]

I think it's a good idea. If you have the data available feel free to add it to your elm-test reports.