I18N and German translation

Hi Kari,

as the code is very well prepared for I18N I took the freedom to provide a German translation.

Note: there are three strings untranslated for PermissionsDialog (Read/Write/Execute), as the translations would have broken the page layout. Not too much of an issue IMO, because anyone who knows how to handle file permissions presumably also knows the English terms :)

Thanks for File Browser - great app :)
Jens