Added simple cron function

Hi Jenn ,
As per the helpdesk ticket 46785, please find the pull request for addition of a simple cron function to go through to all the courses that have Panopto added to their course ( I am determining this from looking at the block_panopto_foldermap table ) . I believe ,initially the reason for us at the institution to create this was to avoid getting too many 'Panopto Ready to view' messages .