Updated online sciebo content does not get re-downloaded locally

[mainrs]

If a Moodle page contains a link and the sciebo module is activated, the program does not re-download the sciebo content if there has been any update to the sciebo folder. All files from the sciebo folder are downloaded once and never again. Users have to manually delete the downloaded archive file to force a re-download with updated content.

The sciebo website generates a request to https://rwth-aachen.sciebo.de/public.php/webdav/ which returns a XML file that can be used to determine the timestamp that the content has been last updated for every single file available.