MDL-16360 - added support for mime-style subformat detection for portfolio supported formats

works well with flickr plugin (tested by uploading an image as a forum attachment and being offered flickr plugin but not for normal attachments)

mod/chat/lib.php

@@ -855,6 +855,7 @@ class chat_portfolio_caller extends portfolio_module_caller_base {
             $select,
             $params
         );
+        $this->supportedformats = array(PORTFOLIO_FORMAT_HTML);
     }
 
     public function expected_time() {