How merchant admins can set up quantity in payment items

Merchant admins are able to define quantity on hand for payment line items; by default the quantity will be disabled (meaning: infinite). However once the Merchant admin enables “payment line item quantity” then the user will be able to limit quantity. When the page renders it will track and display quantity. System will not allow the user to enter more than the quantity.  (i.e.: quantity on hand 5 and user enters 6 – this will not be allowed.)  Once quantity goes to zero then system will not display this item. This new feature will be applicable to all payment line items.