[JENKINS-22303] Should have option to not care about build failure status

- Regression found by injected unit test fixed.
- <label for=...> shouldn't be used because it doesn't work when the configuration item is repeated. Use <label class="attach-previous"> to have your label attach to the previous DOM node instead.
Merge pull request #40 from mixalturek/master

[JENKINS-22303] Should have option to not care about build failure statu...