Better reporting on job array failures

[antgonza]

When a job within a job-array fails, qiita doesn't know if the job failed because the job wasn't able to run properly in barnacle (bad nodes) or because the input/output were incorrect. The issue is that the "job collector" (what we currently name merge-job) will need to check that this happened; the issue is that this is per-job/command dependent (AKA we might need to add this to each plugin). Anyway, opening here to see if we can find a general solution.