Draft: Enable more than one authorship receptor

Closes #231

• New DDAA page in product view.
• New model authorinfo to set a price for author/ddaa receptor. Relation product-price-partner
• Create authourinfo for new products that generate ddaa
• Constrain for ddaa price: Sum of all authorships receptor must be equal to ddaa price.
• Addapt old sales logic (when product that generate ddaa is sold/returned we need to create/update ddaa purchase order of ddaa receptor). Now it works with multiple receptors.
• Migrate data from old field receptora_derecho_autoria to authorinfo.