Added missing return values to two functions, wpsc_cart_tax and wpsc_cart_need_to_recompute_shipping_quotes
Merge pull request #1073 from JeffPyeBrook/pr-missing-retrun-values-in-utility-functions

Added missing return values to two functions, wpsc_cart_tax and wpsc_cart_need_to_recompute_shipping_quotes

Resolves issue #1072