Total revision of german translation
Total revision of german translation

Corrected lots of typos, grammar and incomprehensible (machine?) translation. Things can still be improved but at least most of the strangeness should be gone. I also added all strings from messages.js that were not included before.

Somebody needs to check that I did not mess up code/formatting.
xwiki-labs/cryptpad,xwiki-labs/cryptpad,xwiki-labs/cryptpad