splitFulfillment
List<F> splitFulfillment(F fulfillment,
                         List<Map<String,Integer>> itemQuantities)
Splits the given fulfillment into multiple. The first split fulfillment will contain the
 remainder of the original fulfillment, while the rest will contain the portions requested by
 itemQuantities.
- Parameters:
 
fulfillment - the original fulfillment to split 
itemQuantities - the quantities of each item to put into each fulfillment, with each map
        having the fulfillment item ID as the key, and the quantity to include in that
        fulfillment as the value 
- Returns:
 
- a list containing the original fulfillment now containing the remainder of the
         original fulfillment, and all of the new fulfillments each containing the items
         requested