fix saving m2m in Django<1.9 after #695
fix saving m2m in Django<1.9 after #695

django-import-export/django-import-export,bmihelac/django-import-export,jnns/django-import-export,daniell/django-import-export,bmihelac/django-import-export,copperleaftech/django-import-export,copperleaftech/django-import-export,daniell/django-import-export,copperleaftech/django-import-export,jnns/django-import-export,bmihelac/django-import-export,jnns/django-import-export,django-import-export/django-import-export,django-import-export/django-import-export,copperleaftech/django-import-export,django-import-export/django-import-export,jnns/django-import-export,daniell/django-import-export,daniell/django-import-export,bmihelac/django-import-export