api: also return original avatar for users, fixes #4305

git-svn-id: svn://develop.studip.de/studip/trunk@29960 c5b85792-5220-0410-ad23-ed5b6b8ad999
api: adjust all occurences of user avatars, re #4305

git-svn-id: svn://develop.studip.de/studip/trunk@29961 c5b85792-5220-0410-ad23-ed5b6b8ad999