l10n: de.po: translate 77 new messages

Translate 77 new messages came from git.pot update
in 3b6137f (l10n: Update git.pot (76 new, 4 removed
messages)) and bb2ba06 (l10n: Update one message in
git.pot).

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>

Author: ralfth