update to v.7 use wp_dropdown_categories

git-svn-id: https://plugins.svn.wordpress.org/taxonomy-taxi/trunk@764887 b8457f37-d9ea-0310-8a92-e5e31aec5664
change show none to show all

git-svn-id: https://plugins.svn.wordpress.org/taxonomy-taxi/trunk@764890 b8457f37-d9ea-0310-8a92-e5e31aec5664