Merge pull request #11 from iampersistent/master

add setProductSKU method to ProductManager
Merge pull request #12 from iampersistent/master

add brand mgr, move Spec interface
Merge pull request #13 from iampersistent/master

add Brand persisting & Brand in Product
updates for Cart removal
some test clean up
updates concerning adding products to order
move isValidOpenOrder from OrderProvider to OrderManager
update mapping
refactoring and add tests for isValidOpenOrder
update Brand mapping