[ZDF] Encode file name to ASCII for compatibility
[ZDF] Encode file name to ASCII for compatibility

This ensures that unicode filenames with UTF-8 characters are encoded into ASCII strings, to be compatible to all Pyload methods using `pyfile.name`.
The encoding now is similar to the [YoutubeCom hoster module](https://github.com/pyload/pyload/blob/f61dcaa263750a61f86b4bfbaf9c2cf20c157de0/module/plugins/hoster/YoutubeCom.py#L145).
vuolter/pyload,vuolter/pyload,vuolter/pyload