title: jquery-ui autocomplete for json shows all data when i type into input
body: <p>i have problem with using jquery-ui auto-complete for json. say, my json query return from myurl/users/listid and this is the returning data:</p>
  
  <pre><code>[{"label":"test@gmail.com"},{"label":"omg@hotmail.com"},{"label":"bad@yahoo.com"}]
  </code></pre>
  
  <p>and this is my jquery script for autocomplete.</p>
  
  <pre><code>$("#search-query").autocomplete({
      source: '/users/listid'
  });
  </code></pre>
  
  <p>when i type something into my #search-query input box, this all three email id are shown regardless what i type. it should narrow it down to what it matches to the character i try to type. but it doesn't.</p>
  
  <p>okay. this is something wierd. when i change something like following script, everything works perfect.</p>
  
  <pre><code>var data = [{"label":"test@gmail.com"},{"label":"omg@hotmail.com"},{"label":"bad@yahoo.com"}];
  
  $("#search-query").autocomplete({
      source: data
  });
  </code></pre>
  
  <p>i have totally no idea what has gone wrong. please guide me. thanks.</p>