Improve logging of new job submissions

This addresses issue 290: when receiving new jobs, logging is
incomplete, and we don't have the job ID(s) and/or summaries
logged. Only later, when the job is queried for or being processed, we
know more.

This is not good when troubleshooting, so let's improve the initial
logging.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Bernardo Dal Seno <bdalseno@google.com>