Fix: max limit was ablt to be overridden by adding a new instance of the item to the cart, or by updating quantity on cart page.

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-max-quantity/trunk@857562 b8457f37-d9ea-0310-8a92-e5e31aec5664
Bug fix

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-max-quantity/trunk@857563 b8457f37-d9ea-0310-8a92-e5e31aec5664