Added is_private field on updateListing
Merge branch 'master' of github.com:inakiabt/etsy-php

* 'master' of github.com:inakiabt/etsy-php:
  Correction on scope and callback parameters on request_token
  Update EtsyClient.php
  Added explanation of how to setup specific permissions on request authorization
  Added checks for MacOSX OS on open url
  Update README.md
  Update README.md
  Update README.md
  Update README.md
  Update composer.json
  Update README.md
  Update composer.json
  Update README.md
Request Token method arguments updated