Working HelloWorld test, checks that we can create a task and receive a message from pulseListener.

Hmm... I don't think this task completes successfully. You probably need to specify `maxRunTime`.
See: http://docs.taskcluster.net/docker-worker/
(`maxRunTime` is a required property).

Note, the task still completes.. But the completed message has `message.payload.success == false` indicating that it completed unsuccessfully. This might be some what bad terminology. Basically a task a 3 different resolutions:

 * completed successfully (ran and exited zero)
 * completed unsuccessfully (ran and exited non-zero)
 * failed (task didn't run, because worker kept crashing for unknown reasons, hardware failure, bugs, etc...)