ensuring products can be added with 0 quantity

defaults to 1
Merge branch 'refs/heads/kohana_v3.3/fix/add_product_0_quantity' into kohana_v3.3/master
correcting the cart order select label field

to `order_num`
Merge branch 'refs/heads/kohana_v3.3/fix/cart_order_source_label' into kohana_v3.3/master
disabling the data field in the db admin

since it's serialized
Merge branch 'refs/heads/kohana_v3.3/fix/data_db_admin_show' into kohana_v3.3/master
adding manual additional changes

adding quantity to additional charges
includes reorganizing the Model_Cart_Order::calculate_totals()
Merge branch 'refs/heads/kohana_v3.3/feature/manual_add_charge' into kohana_v3.3/master