use server relative paths in REST API, refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29420 c5b85792-5220-0410-ad23-ed5b6b8ad999
enable REST-API collections of the same super class, refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29421 c5b85792-5220-0410-ad23-ed5b6b8ad999
empower RouteMap#before to do custom routing, #refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29422 c5b85792-5220-0410-ad23-ed5b6b8ad999