Fix 'is not a boolean' in IPNs when retrieving test flag

CRM/Core/Payment/MJWTrait.php

@@ -278,7 +278,7 @@ trait CRM_Core_Payment_MJWTrait {
    * @return bool
    */
   public function getIsTestMode() {
-    return isset($this->_paymentProcessor['is_test']) && $this->_paymentProcessor['is_test'] ? TRUE : FALSE;
+    return isset($this->_paymentProcessor['is_test']) && $this->_paymentProcessor['is_test'] ? 1 : 0;
   }
 
   /**