Adding German translation

[kennymc-c]

This adds a German translation. I also removed the duplicate account key inside cli/local.

[joeyates]

Hi @kennymc-c

Thanks for this. i18n has been merged for 2 days, and there's already a contributed language, perfect!

Thanks, also for pointing out the repeated key under cli.local - I'll fix that in the other languages.

Just one niggle - I don't think UNSEEN should be translated, but I'll alter that with the other change.