Revert "remove htmlpurifier"

This reverts commit c21a462d52.

lib/htmlpurifier/library/HTMLPurifier/URIScheme/http.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * Validates http (HyperText Transfer Protocol) as defined by RFC 2616
+ */
+class HTMLPurifier_URIScheme_http extends HTMLPurifier_URIScheme {
+
+    public $default_port = 80;
+    public $browsable = true;
+    public $hierarchical = true;
+
+    public function doValidate(&$uri, $config, $context) {
+        $uri->userinfo = null;
+        return true;
+    }
+
+}
+
+// vim: et sw=4 sts=4