fixing price filter when 1 or less options provided

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-ajax-filters/trunk@1055711 b8457f37-d9ea-0310-8a92-e5e31aec5664
changing version number in files

git-svn-id: https://plugins.svn.wordpress.org/woocommerce-ajax-filters/trunk@1055713 b8457f37-d9ea-0310-8a92-e5e31aec5664