Casting return of Validation::ip to always be a boolean when filter_v…

…ar is used. It used to return the input string which could cause issue with identity checks.

cake/libs/validation.php

@@ -549,7 +549,7 @@ function extension($check, $extensions = array('gif', 'jpeg', 'png', 'jpg')) {
  */
 	function ip($check, $type = 'IPv4') {
 		if (function_exists('filter_var')) {
-			return filter_var($check, FILTER_VALIDATE_IP);
+			return (boolean) filter_var($check, FILTER_VALIDATE_IP);
 		}
 
 		$_this =& Validation::getInstance();