Fixed bug reported by Adrian Crum and introduced with the promotion engine refactoring that I committed in rev. 1554265: under some conditions an "ArithmeticException: Non-terminating decimal expansion" could be thrown by the new ShoppingCart$ProductPromoUseInfo.getUsageWeight() method due to missing scale and rounding mode; this method computes a "weight" for the "promotion use" that is used to sort promotions to be applied.

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1558145 13f79535-47bb-0310-9956-ffa450edef68