Note, these functions only cancel a job in progress. If your
download is already prepared for you, this won't do anything to change
that.
occ_download_cancel
cancels a specific job by download key - returns
success message
occ_download_cancel_staged
cancels all jobs with status RUNNING
or PREPARING
- if none are found, returns a message saying so -
if some found, they are cancelled, returning message saying so