Update autoslugfield to not use get_fields_with_model()
Update autoslugfield to not use get_fields_with_model()

Method get_fields_with_model() isn't available in Django 1.10 so replace with
_get_fields().

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