fix favicon on error document page

rhodecode/templates/errors/error_document.html

@@ -5,7 +5,7
         <title>Error - ${c.error_message}</title>
         <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
         <meta name="robots" content="index, nofollow"/>
-        <link rel="icon" href="${h.url('/images/icons/database_gear.png')}" type="image/png" />
+        <link rel="icon" href="${h.url('/images/favicon.ico')}" type="image/png" />
 
         <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
         %if c.redirect_time: