Fix and test report urls for unknown failures

The failure-url is not used when formatting jobs with a result of e.g.
POST_FAILURE or TIME_OUT. Fix this by defaulting to the failure-url
for any non-success result.

This also enhances the test_playbook test with a broken post playbook
and tests for the correct urls.

Change-Id: I8485dee83e36275a1dd439f12cf8c0fdf90999ca
5 files changed