Add a visual indicator that tests have failed on the overview page like in the warnings-ng plugin.

Colleagues keep wondering why the receive "build failed" mails even though everything looks ok on the build overview page. They are all missing the failed tests because the warnings ng plugin has such a strong "green" visual indicator that everything is ok.

This is the output of a failed build:

This is the output of a successful build:

Hardly any difference at all.

A visual indicator like the following for builds that became unstable or failed because of failing tests would be very helpful.