Add json trace logging.

We would like to be able to capture some json messages from production
so we can use that to create realistic test data.
Make sure CSA does not throw an error for unknown Jira task status.

Previously CSA threw an IllegalStateException when the
remoteIssue.getStatus returned a, for CSA, unknown status. Now we just
return Status.OPEN for those issues.
Log an ERROR when synchronising with JIRA failed.

Previously any IOException that occurred when trying to synchronise with
JIRA was logged as WARN. This could result in the fact that JIRA is not
synchronised for days without noticing.