title: Polymer: Rendering looped JSON
body: <p>I've seen a few answer to this but for some reason I can't wrap my head around why this isn't working. I'm trying to get the values of a JSON array and output them in custom HTML elements in my template.</p>
  
  <p>Polymer Element:
      </p>
  
  <pre><code>&lt;polymer-element name="graph-optionsLoad"&gt;
      &lt;template&gt;
          &lt;core-ajax auto url="/getDataHeaders"
                 handleAs="json" response="{{headerList}}"&gt;&lt;/core-ajax&gt;
          &lt;div&gt;TEST&lt;/div&gt;
          &lt;ul&gt;
              &lt;template repeat="{{h in headerList}}"&gt;
                  &lt;li&gt; {{h}}&lt;/li&gt;
              &lt;/template&gt;
          &lt;/ul&gt;
  
      &lt;/template&gt;
  
      &lt;script&gt;
          Polymer( "graph-optionsLoad", { 
          headerListChanged: function(oldValue) {
              console.log(this.headerList);
              // this.headers;
              }
          });
  
  
      &lt;/script&gt;
  &lt;/polymer-element&gt;
  </code></pre>
  
  <p>JSON:</p>
  
  <pre><code>{
  "headers": [
  "MakeSpawnFish",
  "MakeEndGame",
  "MakeModeChange",
  "MakeConnectComponent",
  "MakeCircuitCreated",
  "MakeStartGame",
  "MakeSnapshot",
  "MakeResetBoard",
  "MakeAddComponent",
  "MakeCaptureFish",
  "MakeRemoveComponent",
  "MakeDisconnectComponent"
  ]
  }
  </code></pre>
  
  <p>HTML</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;head&gt;
          &lt;script src="/static/bower_components/webcomponentsjs/webcomponents.js"&gt;&lt;/script&gt;
  
          &lt;link rel="import" href="/static/bower_components/my-elements/graph-optionsLoad.html"&gt;
          &lt;link rel="import" href="/static/bower_components/core-ajax/core-ajax.html"&gt;
  
          &lt;!-- &lt;link rel="import" href="/static/greeting-tag.html"&gt; --&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
      &lt;graph-optionsLoad&gt;&lt;/graph-optionsLoad&gt;
  
      &lt;script&gt;
  
      &lt;/script&gt;
      &lt;/body&gt; 
  &lt;/html&gt;
  </code></pre>
  
  <p>All that seems to show up on the page is the "TEST" and the empty <code>&lt;ul&gt;&lt;/ul&gt;</code></p>