implemented alt_folder and reorganized interface class code

content-controllers/url/url.controller.php

@@ -0,0 +1,9 @@
+<?php 
+
+class UrlController implements ContentController
+{
+    //returns all extensions registered by this type of content
+    public function getRegisteredExtensions(){return array('url');}
+    public function handleHash($hash,$url){}
+    public function handleUpload($tmpfile,$hash=false){}
+}