Tag 500 should write problematic lines with escapeHtml

It is already fixed with the new auto-escape in HTML templates.

This is still a problem if one decides to not use the automatic html escaping

Ok we can't fix it this way:

For instance:

--------------------------------------------
package controllers;

import play.mvc.*;

public class Application extends Controller {

 public static void index() {
   render("not_exist_template.html");
 }
}

------------------------------
Template Not Found:
9 render("not_exist_template.html");

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i changed the 500.html's
<pre>&nbsp;${line.escapeHtml()}</pre>
line to:
<pre>&nbsp;${line.raw()}</pre>