title: Preselect a default page in iron-pages when using with paper-tabs
body: <p>I am using Polymer <code>iron-pages</code> along with <code>paper-tabs</code> in my rails app. The problem is none of pages were shown until one of the <code>paper-tabs</code> was clicked. I want the first page in <code>iron-pages</code> to be selected by default without user interaction.     </p>
  
  <p>I have put both <code>paper-tabs</code> and <code>iron-pages</code> in a <code>&lt;template is='dom-bind'&gt;&lt;/template&gt;</code>. Have read documentation about data binding, But I couldn't figure out how to achieve this. Please somebody suggest your valuable suggestions. Thank you.</p>
  
  <pre><code>&lt;template is="dom-bind"&gt;
    &lt;div class="middle"&gt;
      &lt;paper-tabs class="bottom self-end" selected="{{selected}}"&gt;
        &lt;paper-tab&gt;Page 1&lt;/paper-tab&gt;
        &lt;paper-tab&gt;Page 2&lt;/paper-tab&gt;
      &lt;/paper-tabs&gt;
    &lt;/div&gt;
    &lt;div class="bottom"&gt;
      &lt;iron-pages selected="{{selected}}"&gt;
        &lt;div&gt; Page 1(This should be selected by default.)
        &lt;/div&gt;
        &lt;div&gt; Page 2
        &lt;/div&gt;
      &lt;/iron-pages&gt;
    &lt;/div&gt;
  &lt;/template&gt;
  </code></pre>