po/TEAMS: add new member to German translation team

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
l10n: de.po: change Email to E-Mail

Change all Email to E-Mail, as this is the correct form in German.

Signed-off-by: Phillip Sz <phillip.szelat@gmail.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
l10n: de.po: use comma before "um"

This patch adds a comma before the "um". See:
http://www.duden.de/sprachwissen/rechtschreibregeln/komma#K117

Signed-off-by: Phillip Sz <phillip.szelat@gmail.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>