Updated changelog for 1.5b2.
Updated changelog for 1.5b2.

jwinzer/OpenSlides,tsiegleauq/OpenSlides,FinnStutzenstein/OpenSlides,emanuelschuetze/OpenSlides,ostcar/OpenSlides,normanjaeckel/OpenSlides,emanuelschuetze/OpenSlides,ostcar/OpenSlides,CatoTH/OpenSlides,boehlke/OpenSlides,rolandgeider/OpenSlides,jwinzer/OpenSlides,normanjaeckel/OpenSlides,OpenSlides/OpenSlides,boehlke/OpenSlides,FinnStutzenstein/OpenSlides,rolandgeider/OpenSlides,FinnStutzenstein/OpenSlides,tsiegleauq/OpenSlides,normanjaeckel/OpenSlides,CatoTH/OpenSlides,boehlke/OpenSlides,OpenSlides/OpenSlides,FinnStutzenstein/OpenSlides,jwinzer/OpenSlides,CatoTH/OpenSlides,emanuelschuetze/OpenSlides,tsiegleauq/OpenSlides,jwinzer/OpenSlides,emanuelschuetze/OpenSlides,jwinzer/OpenSlides,rolandgeider/OpenSlides,ostcar/OpenSlides,boehlke/OpenSlides,normanjaeckel/OpenSlides,CatoTH/OpenSlides