title: Facebook login/logout buttons on Facebook App using PHP
body: <p>I created an app on my website that uses facebook to post photos my facebook albums using PHP.</p>
  
  <p>I would like to further enhance it by doing the following:</p>
  
  <ol>
  <li><p>In order to use the app - I would like a login/logout (I think this can be done but I do not know how)</p></li>
  <li><p>In order for the visitors to use the app the would have to have pressed 'Like' on my page to use this app.</p></li>
  </ol>
  
  <p>Thank you.</p>