Offer to write file to cron.daily to remove temporary files

[aubreyja]

E.g.

WEBWORK_ROOT=/opt/webwork/webwork2
*/30 * * * * find /var/www/wwtmp/*/hardcopy/*  -mmin +60  -name "*" -delete
5 5 1,15 * *  find /var/www/wwtmp/*/gif/  -mtime +30  -name "*" -delete
5 5 2,16 * *  find /var/www/wwtmp/*/png/  -mtime +30  -name "*" -delete
5 5 3,17 * *  find /var/www/wwtmp/*/html/  -mtime +30  -name "*" -delete
4 5 * * 0 /opt/webwork/webwork2/bin/remove_stale_images --delete --days 14