Refactor add product view

[maerteijn]

So I can override the validate method in the view like this:

from oscarapi.views.basket import AddProductView as _AddProductView

class AddProductView(_AddProductView):
    def validate(self, basket, product, quantity):
        # check if there is a orderlimit for this product
        allowed, message = basket.add_product_allowed(product, quantity)
        if not allowed:
            return False, message
        return super(
            AddProductView, self).validate(basket, product, quantity)

[specialunderwear]

not ok, the serializer has been updated, so all properties are available on the cleaned and validated object:

product = p_ser.object['url']
quantity = p_ser.object['quantity'] <-- that one is wrong
options = p_ser.object.get('options', [])