fix import of QueryWrapper for django 1.4
fix import of QueryWrapper for django 1.4

djangonauts/django-hstore,pombredanne/django-hstore,pombredanne/django-hstore,djangonauts/django-hstore,Stranger6667/django-hstore,Stranger6667/django-hstore,djangonauts/django-hstore,pombredanne/django-hstore,djangonauts/django-hstore,Stranger6667/django-hstore,Stranger6667/django-hstore,pombredanne/django-hstore