Updated Invoicing APIs

- Updated Model objects.
- Updated Samples.
- Updated Tests.

lib/PayPal/Api/Address.php

@@ -17,7 +17,7 @@ class Address extends BaseAddress
      * Phone number in E.123 format.
      *
      * @param string $phone
-     *
+     * 
      * @return $this
      */
     public function setPhone($phone)