Modify logs to show "deferred" job status

As @reprazent suggested in &1004 (comment 1396986624), the job_status in the Sidekiq logs should be deferred instead of done as it can be confusing.

Instead of:

{"job_status": "start", ...}
{"message": "Deferring ...} # This also doesn't look like a regular job message
{"job_status": "done", ...}

The logs should be:

{"job_status": "start", ...}
{"job_status": "deferred", ...}