l10n: de.po: translate 70 new messages

Translate 70 new messages came from git.pot update in 25eab54
(l10n: git.pot: v2.15.0 round 1 (68 new, 36 removed)) and 9c07fab
(l10n: git.pot: v2.15.0 round 2 (2 new, 2 removed)).

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>

Author: ralfth