#3574 removed checkOldUser and checkNewUser 

git-svn-id: svn://develop.studip.de/studip/trunk@26920 c5b85792-5220-0410-ad23-ed5b6b8ad999
remove old api calls re #3574

git-svn-id: svn://develop.studip.de/studip/trunk@26921 c5b85792-5220-0410-ad23-ed5b6b8ad999