title: Type ahead - problems with json structure
body: <p>So I've been wrestling with learning Twitter's typeahead.js, and I got to say, the documentation leaves something to be desired. I've tried close to a dozen different methods I found posted around for adding the typeahead functionality to this input and I'm stumped. What, if anything am I missing in the below code? I'm not seeing any errors in the console, and idNums seems to contain the appropriate data, but I'm still not seeing the correct overlay.</p>
  
  <p>My javascript:</p>
  
  <pre><code>    var idNums = new Bloodhound({
                      datumTokenizer: function (datum) { return Bloodhound.tokenizers.whitespace(datum.value);},
                      queryTokenizer: Bloodhound.tokenizers.whitespace,
                      prefetch: 'endpoint that returns below json',
                  });
  
  idNums.initialize();
  
      $('#prefetch .typeahead').typeahead({
                          hint: true,
                          highlight: true,
                          minLength: 1
                  }, 
                  {
                    name: 'BR_NUM',
                    displayKey: 'value',
                    source: idNums.ttAdapter(),
                  });
  </code></pre>
  
  <p>My HTML:        </p>
  
  <pre><code>&lt;div id = "prefetch"&gt;
      &lt;label&gt;Value:  &lt;/label&gt;
      &lt;input  type = "text" name = "Value" class="typeahead" placeholder="ID Number"/&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>This is my json file:</p>
  
  <pre><code> [{
            "BR_NUM":"20512"
         },
         {  
            "BR_NUM":"22788"
         },
         {  
            "BR_NUM":"22789"
         },
         {  
            "BR_NUM":"22790"
         },
         {  
            "BR_NUM":"22791"
         },
         {  
            "BR_NUM":"22792"
         },
         {  
            "BR_NUM":"22793"
         },
         {  
            "BR_NUM":"22794"
         }
      ]
  </code></pre>
  
  <p>EDIT: So If I understand correctly, my code would look like this without the ajax call? or am I removing more than I should?</p>
  
  <pre><code>$('.typeahead').typeahead({
          hint: true,
          highlight: true,
          minLength: 2,
          limit: 8
      }, {
  name: "main-search",
  displayKey: "BR_NUM",
  source: 'json url here'
  </code></pre>
  
  <p>});</p>