title: Display active language flag with Bootstrap
body: <p>Here is <a href="http://www.johanndacosta.fr/" rel="nofollow">my website</a>.</p>
  
  <p>As you can see on the top-right, I managed to display a dropdown menu with language selector inside. Now I want to display the active flag in the navbar.</p>
  
  <p>Any idea?</p>