Bulk Discount compatibility with WooCommerce 2.1.x

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-bulk-discount/trunk@862945 b8457f37-d9ea-0310-8a92-e5e31aec5664
small text change in readme.txt

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-bulk-discount/trunk@863129 b8457f37-d9ea-0310-8a92-e5e31aec5664
text change in readme.txt

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-bulk-discount/trunk@864851 b8457f37-d9ea-0310-8a92-e5e31aec5664