title: Facebook app creation app domain error
body: <p>I'm trying to create Facebook app.
  Yet I had trouble right after creation wizard done his work.</p>
  
  <p>Changing nothing in what wizard created I've got an error:</p>
  
  <pre><code>Error
  You have specified an App Domain but have not specified a valid integration URL.
  secure-citadel-xxxx.herokuapp.com must be derived from one of: Site URL, Mobile
  Site URL, Canvas URL, Secure Canvas URL, Page Tab URL or Secure Page Tab URL.
  </code></pre>
  
  <p>I googled it and found no answer at what it might be..</p>
  
  <p>Adding <code>http://</code> and so on doesn't make anything more than another error of domain being invalid.</p>
  
  <p>Does anyone know ho to deal with it?</p>