Allow ordering job list by different task counts

queued / running / failed / done
Allow NULL values for Job.state
Allow "next" request arg for rerun single job
Implement single job user interface
Add Pause/Unpause function to single job view
When pausing job, stop running tasks
Fix minor typo in logstring
Call scheduler on unpausing/rerunning a job
Reset attempts on tasks when rerunning a job
Remove microsecond precision from times in job UI

The microsecond precision adds no real value and only clutters up the
view.
Round task percentages to two fractional digits
Make sure tasks are always ordered by frame
Allow altering frame selection on job via UI
Allow changing scheduler parameters for job via UI
Add notes field to single job view in UI