job reseting.  This allowed direct UPDATE..WHERE.. sql to be used.
Also changed the retry_count system: retry_count is only incremented
for jobs that failed (status in ('GET_INPUT','RUN','WRITE_OUTPUT')).
Job that were CLAIMED by the dead worker are just reset without
incrementing the retry_count since they were never attempted to run.
Also the fetching of claimed jobs now has an 'ORDER BY retry_count'
so that jobs that have failed are at the bottom of the list of jobs
to process.  This allows the 'bad' jobs to filter themselves out.