Issue #108: Adding German translations

[crud3]

I have added the missing German translations mentioned in #108 and also translated the submitapp string.

Some Remarks / Questions:

• I could also translate the themes strings ("Light", "Dark") if you want, but I personally think that would sound very forced/unnatural. Many German Apps/Programs just use "Light" and "Dark" and don't translate it.
• I also copied the "themesValues" array from the values.xml because it appeared in the error log. Is that correct or should I remove it?

[bobheadxi]

Thanks! 🎊 If you don't think the themes need translating they should be fine. themesValues probably shows up on the errors simply because they are absent, but adding them should be harmless