refactored new_sale function
refactored new_sale function

Neschur/spree-sale-pricing,redglory/spree_sale_prices,Neschur/spree-sale-pricing,Neschur/spree-sale-pricing,renuo/spree_sale_prices,renuo/spree_sale_prices,redglory/spree_sale_prices,redglory/spree_sale_prices