adding a contact twice should result in a 201, refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29856 c5b85792-5220-0410-ad23-ed5b6b8ad999
use correct method, refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29857 c5b85792-5220-0410-ad23-ed5b6b8ad999