title: Unable to set checked as a default - knockout checkbox
body: <p>I'm new in knockout and I couldn't solve a little problem, which is to set a checkbox as a default selected.</p>
  
  <p>HTML:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;tr&gt;
      &lt;td&gt;
          &lt;input id="summary" type="checkbox" checked="checked" data-bind="checked: Summarise"/&gt; 
          Summary 
      &lt;/td&gt;
  &lt;/tr&gt;
  </code></pre>
  
  <p>Doc.Ready:</p>
  
  <pre><code>if (!viewModel) {
      viewModel = new ViewModel();
  }
  
  ko.applyBindings(viewModel, document.getElementById("ParametersView"));
  </code></pre>
  
  <p>This returns unchecked checkbox when it gets called.</p>