verify_packages_published: highlight errors in gubernator
verify_packages_published: highlight errors in gubernator

Gubernator highlights lines with `fail` and `error`.

Makes it possible to view the versions with missing packages
directly on this page:
  https://k8s-gubernator.appspot.com/build/kubernetes-jenkins/logs/periodic-kubernetes-e2e-packages-pushed/120

instead of requiring to click "Raw build-log.txt".

kubernetes/kubeadm,kubernetes/kubeadm