load german language for babel

Some references declare `language=german`.
As the old german language is not loaded by babel this results in a compilation
error.

Changes have been made to all .tex files with:

`$ find -name '*tex' -type f | xargs sed -i -r 's/([[:alnum:]]*), ([[:alnum:]]*)\]\{babel\}/\1, german, \2\]\{babel\}/'`