Format JSP page using <jtidy:tidy> tag

To do this:

• define tag extension <%@ taglib uri="http://jtidy.sf.net" prefix="jtidy" %>
• the page code should be inside <jtidy:tidy> JSP tag
• optionaly include <jtidy:validationImage/> inside common JSP header to see if the page you are testing is well formatted.