/** Sanitizes invalid server var value, except PHP_AUTH_USER and PHP_AUTH_PW 
	 * must call ::logValidationWarning if replacing some character(s) that raise security suspicion 
	 * default implementation is no sanitization.  
	 * May be overridden on HttpValidator to do actual sanitization.
	 * @return mixed sanitized and validated value or null
	 * @param string value that has failed validation 
	 * @trhows PntValidationException if validation fails after sanitization
	 * */
	function sanitizeServerValue($name, $value) {
		return $value; 
	}