Sets "no cache" response headers
HttpServletResponse response =
(HttpServletResponse) pageContext.getResponse();
response.addHeader("Pragma", "No-Cache");
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
response.addHeader("Cache-Control", "pre-check=0, post-check=0");
response.setDateHeader("Expires", 0);
return EVAL_PAGE;