Modify DjangoModelPermissions to return True if get_required_permissions() yields an empty list

I have a class derived from ListCreateAPIView, which I want it to use DjangoModelPermissions. GETs from an AnonymousUser were returning False, since the user was not authenticated. But since 

perms = self.get_required_permissions(request.method, model_cls)

was an empty list, it should be returning true. Hence the change. Let me know if it doesn't make sense! cheers