re #4525 delete unused admin page

git-svn-id: svn://develop.studip.de/studip/trunk@31614 c5b85792-5220-0410-ad23-ed5b6b8ad999
re #4609 background resized

git-svn-id: svn://develop.studip.de/studip/trunk@31615 c5b85792-5220-0410-ad23-ed5b6b8ad999
re #4609 new image

git-svn-id: svn://develop.studip.de/studip/trunk@31616 c5b85792-5220-0410-ad23-ed5b6b8ad999