Larger files may remain in system temp directory

The Zip workflow operation handler will create zip archives by copying all files belonging to a media package to a temporary directory and then zipping this directory. If Opencast is inconveniently sut down, these temporary files will stay there forever. Furthermore, the location of the directory is poorly chosen since this is often not the same storage space used by the workspace. Hence no hard linking of files can be used which slows down the operation.