fixed jsonfield for django 1.5
fixed jsonfield for django 1.5

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