l10n: add new members to German translation team

Add Thomas Rast, Jan Krüger and Christian Stimming
to German translation team.
Signed-off-by: NRalf Thielow <ralf.thielow@googlemail.com>

po/TEAMS

@@ -8,6 +8,9 @@ Leader:		Byrial Jensen <byrial@vip.cybercity.dk>
 Language:	de (German)
 Repository:	https://github.com/ralfth/git-po-de
 Leader:		Ralf Thielow <ralf.thielow@googlemail.com>
+Members:	Thomas Rast <trast@student.ethz.ch>
+		Jan Krüger <jk@jk.gs>
+		Christian Stimming <stimming@tuhh.de>
 
 Language:	is (Icelandic)
 Leader:		Ævar Arnfjörð Bjarmason <avarab@gmail.com>