loosens up zipcode validator to accept 4 digit zipcodes (valid in the US).

src/js/validator/zipCode.js

@@ -34,7 +34,7 @@
                     return /^(S-)?\d{3}\s?\d{2}$/i.test(value);
                 case 'US':
                 default:
-                    return /^\d{5}([\-]\d{4})?$/.test(value);
+                    return /^\d{4,5}([\-]\d{4})?$/.test(value);
             }
         }
     };