Updated German translation

[entusdictus]

Updated translation to use "Du/Dein" in favor of "Sie/Ihr" to match with the current German macOS translation, grammar fixes.

[AirBookMac]

@entusdictus Hi Michael, where and how can i implement this?

[entusdictus]

As this is a pull request, this needs to be approved before it makes its way into the project. You can of course fork the current release, implement the translation on your own and create your own build of Nudge until this pull request gets approved ;)