- fix handling of datafields while migrating users
- migrate avatars as well
- post notification before and after migration
- adjust view


git-svn-id: svn://develop.studip.de/studip/trunk@26461 c5b85792-5220-0410-ad23-ed5b6b8ad999
Subtile Veränderung des Randes re #3416

git-svn-id: svn://develop.studip.de/studip/trunk@26462 c5b85792-5220-0410-ad23-ed5b6b8ad999