optimize images from [27007] for size, re #3551

git-svn-id: svn://develop.studip.de/studip/trunk@27012 c5b85792-5220-0410-ad23-ed5b6b8ad999
optimize images from [27004] for size, re #3551

git-svn-id: svn://develop.studip.de/studip/trunk@27013 c5b85792-5220-0410-ad23-ed5b6b8ad999