title: get domain name (base url without protocol)
body: <p>How to get app domain name? (I mean base url without protocol <code>http://</code> or <code>https://</code>)</p>
  
  <p>So if app is installed on '<a href="http://sub.example.com/app" rel="nofollow">http://sub.example.com/app</a>', I want to get 'sub.example.com'.</p>