Do not block workflow when gerrit connection is broken

[cdir]

Seems like it was already considered. In NoOpenReviews I found the comment:

 // If there's an error, best not to block the workflow, and just act like it passes??

followed by

throw new WorkflowException(e);

I think it is way better to not block the workflow. At the moment we cannot close any subtask while having issue #70. Maybe there is an easy way to show a warning in this case.