title: Firebase custom unique ID
body: <p>In my EmberFire app the URL looks like this:</p>
  
  <pre><code>http://example.com/friends/-Jaxji0depwt4PE8KnFG
  </code></pre>
  
  <p>Is there a way to customize the unique ID in Firebase to look like this:</p>
  
  <pre><code>http://example.com/friends/1
  http://example.com/friends/2
  http://example.com/friends/3
  </code></pre>