Updated Changlog for 1.3 release.
Updated Changlog for 1.3 release.

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