Fix Screen Print White Under Base Price Logic

See images for common miscalculated print colours.

A big chunk of our quotes are inaccurate because the under base function does not take into account the print colours (specifically black/white) being used. 

Easy logic fix to cover most (but not all) scenarios:

IF white in artwork = don't charge for under base

IF no white in artwork, dark garment = charge for under base 

IF ONLY black ink in artwork = don't charge for under base