Periodic-task-runtimes.sh: Use date ended instead of date started.
Periodic-task-runtimes.sh: Use date ended instead of date started.

mitsuhiko/celery,cbrepo/celery,frac/celery,WoLpH/celery,ask/celery,WoLpH/celery,mitsuhiko/celery,cbrepo/celery,ask/celery,frac/celery