Fix rendering of json response in the basket view.
Fix rendering of json response in the basket view.

The render_to_string() function doesn't accept an RequestContext
anymore since 1.10

django-oscar/django-oscar,django-oscar/django-oscar,sasha0/django-oscar,django-oscar/django-oscar,solarissmoke/django-oscar,sonofatailor/django-oscar,sonofatailor/django-oscar,sasha0/django-oscar,sonofatailor/django-oscar,solarissmoke/django-oscar,solarissmoke/django-oscar,sonofatailor/django-oscar,solarissmoke/django-oscar,sasha0/django-oscar,sasha0/django-oscar,django-oscar/django-oscar