Changed behavior to access_token parameter in get / post method

If request URL has access_token parameter, this module shouldn't add access_token to the URL.

As a example, if using client_credentials, an application adds access_token in request URL.
https://developers.facebook.com/docs/howtos/login/login-as-app/

This module always add user's access_token. If request URL has access_token, this module shouldn't add user's access_token, I think.