Validation Package Testing

- Added More Unit Tests to Validation Classes
- Updated Logic accordingly

lib/PayPal/Validation/JsonValidator.php

@@ -19,7 +19,7 @@ class JsonValidator
      */
     public static function validate($string, $silent = false)
     {
-        json_decode($string);
+        @json_decode($string);
         if (json_last_error() != JSON_ERROR_NONE) {
             if ($silent == false) {
                 //Throw an Exception for string or array