cyber-dojo traffic lights

Press and stdout+stderr+status are displayed in the output tab, and you get a new traffic-light.
Each traffic-light is coloured:

• red if the tests ran but one or more failed.
• amber if the tests did not run, eg syntax error.
• green if the tests ran and all passed.
• if the tests did not complete in ~10 seconds.

If test-prediction is enabled (click the cog/gear icon to open the settings dialog), traffic-lights look like this:

• correct prediction (of green).
• incorrect prediction (of red or amber).
• auto-revert (back to green).

Click any traffic-light to open the history page showing:

• diffs for any traffic-light's files, for any animal.
• a button to checkout (git checkout) the files from any traffic light.
• a button to fork a new exercise from any traffic light's files.