* renamed test.php to tests.php since it now has links to multiple tests
* removed some commented-out code
* renamed the 'language_attributes' hook function to be consistent with the filter name
* use the pattern of storing WP_Error objects and returning FALSE when we encounter an error, instead of returning WP_Error objects
* lazily instantiate oauth or facebook client objects
* use 'app_id' and 'secret' for facebook's oauth credentials to be consistent with facebook's usage