German translation, first iteration

Here the german translation as discussed in ServerGrove support ticket 328373. When the translations are live in the system it may be that I have some more changes when I realize that I translated something out of context. Already includes the changes (the deletions as well as the additions) in https://github.com/pgodel/sgcontrol-translations/commit/2a3e9a97da49646e7ea7e6d7e174243542630505 in Pablos fork.