Removed unused 'category' property on Line model.
Removed unused 'category' property on Line model.

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