refs #3239: all users got tutor perms accidentaly

git-svn-id: svn://develop.studip.de/studip/trunk@25517 c5b85792-5220-0410-ad23-ed5b6b8ad999
refs #3239: fix migration of user-visit-dates, to work with an already present installation of the forum-plugin

git-svn-id: svn://develop.studip.de/studip/trunk@25518 c5b85792-5220-0410-ad23-ed5b6b8ad999