Add import of brand to productlist import

[fsmanuel]

at the moment the productlist import seems to ignore the brand of the product uploaded. sometimes a supplier has the same product available from two brands like "peanutbuttter with seasalt". to differentiate between these products (amongst other for creating a product id) and show members from which brand the product is (some members have strong preferences for their favorit brand of peanutbutter)

solution proposal
Add import of brand into productlist in foodsoft but not making the brand a required field (because veggies usually do not have a brand)