l10n: de.po: translate 68 new messages

Translate 68 new messages came from git.pot update in
f4f2c8f (l10n: git.pot: v2.7.0 round 1 (66 new, 29 removed)) and
2c0ca05 (l10n: git.pot: v2.7.0 round 2 (2 new, 2 removed)).

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Acked-by: Matthias Rüster <matthias.ruester@gmail.com>