enable running current tests on php >= 5.5; re #4445

git-svn-id: svn://develop.studip.de/studip/trunk@31262 c5b85792-5220-0410-ad23-ed5b6b8ad999
mock Config class to run getMediaUrl test; re #4445

git-svn-id: svn://develop.studip.de/studip/trunk@31263 c5b85792-5220-0410-ad23-ed5b6b8ad999