api: add datafields to user route, fixes #4140

git-svn-id: svn://develop.studip.de/studip/trunk@29271 c5b85792-5220-0410-ad23-ed5b6b8ad999
api: fix avatar access, fixes #4153

git-svn-id: svn://develop.studip.de/studip/trunk@29272 c5b85792-5220-0410-ad23-ed5b6b8ad999