updated the plugin version to 1.8.0

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-mercadopago/trunk@814841 b8457f37-d9ea-0310-8a92-e5e31aec5664
removed extra files

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-mercadopago/trunk@814842 b8457f37-d9ea-0310-8a92-e5e31aec5664