title: Wait until converse.js joins room
body: <p>Is there a way through which we can wait until converse.js has joined a room? And once we have joined, we receive some sort of event ? I see that the converse documentation has a tag that can wait until converse.js has fully loaded</p>
  
  <pre><code>_converse.on('connected', function () { ... });
  </code></pre>
  
  <p>I was wondering if there is a way to call this API from JS on webapage ?</p>