title: Unable to load the requested class: Facebook using facebook php sdk codeigniter
body: <p>I want to login with facebook using facebook sdk php in codeigniter.</p>
  
  <p>i have use facebook libary in applications/libraries/Facebook.php</p>
  
  <p>and full sdk path in applications/vendor</p>
  
  <p>config of my facebook app_id and app_secret in config folder config/facebook.php</p>
  
  <p>in autoload.php i load facebook library</p>
  
  <pre><code>$autoload['libraries'] = array('facebook','database','form_validation','session');
  </code></pre>
  
  <p>But i got an error Unable to load the requested class: Facebook</p>