Add relation between order and cart
	modified:   schema.xml
	modified:   thelia2_model.mwb
	modified:   thelia2_model.png
Merge pull request #18 from lovenunu/order-carts

Add relation between order and cart
Added visible argument for image and document related classes.
Merge pull request #19 from bibich/improvements

Added visible argument for image and document related classes.
Added a PK to the sale_product table
Merge pull request #20 from roadster31/sales-attributes

Added a PK to the sale_product table