Fix mount point discovery after udisks2 switched from /media to /run/media

As of udisks 2.10.91, the mount point for removable media is wrongly detected due to an outdated and hardcoded list of distributions in rapid-photo-downloader.

I decided to remove this hardcoded distribution list and completely rely on runtime detection of the proper directory. This also won't break backports in case that this becomes relevant.

This MR adds a patch for the change described above, as well as at bit housekeeping.