WC 2.2 compatibility fix

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-products-per-page/trunk@987033 b8457f37-d9ea-0310-8a92-e5e31aec5664
readme date update

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-products-per-page/trunk@987034 b8457f37-d9ea-0310-8a92-e5e31aec5664