title: knockout does not set an initial true value on radio button
body: <p>The 1-way binding for the names + checkbox works fine, but it does not work initially for the radio button employeeTypeA although its value is true in the viewmodel the html shows the radio button as not set, why is that?</p>
  
  <pre><code>   &lt;script type="text/javascript"&gt;
  
          $(function()
          {
              var PersonViewModel = function()
              {
                  this.firstName = ko.observable('Lisa');
                  this.lastName = ko.observable('T');
                  this.isCustomer = ko.observable(true);
                  this.employeeTypeA = ko.observable(true);
                  this.employeeTypeB = ko.observable(false);
              };
  
              var personViewModel = new PersonViewModel();
              ko.applyBindings(personViewModel, $('data').get(0));
          });
      &lt;/script&gt;
  
      &lt;div id="data"&gt;
          &lt;span data-bind="text: firstName"&gt;&lt;/span&gt;
          &lt;span data-bind="text: lastName"&gt;&lt;/span&gt;
          &lt;input type="checkbox" data-bind="checked: isCustomer" title="Is a customer" /&gt;
          &lt;input name="x" type="radio" data-bind="checked: employeeTypeA" title="Employee type A" /&gt;
          &lt;input name="x" type="radio" data-bind="checked: employeeTypeB" title="Employee type B" /&gt;
      &lt;/div&gt;
  </code></pre>