title: knockoutjs optionsCaption for options and select binding
body: <p>I have the following markup for my viewmodel:</p>
  
  <pre><code>&lt;select data-bind="
      foreach: $parent.Activities,
      value: ActivityId,
      optionsCaption: 'Please select'" 
      class="iaActivities"&gt;
  
      &lt;option data-bind="
              value: Id,
              text: Name,
              attr: { 'title': Name }"&gt;&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>The options are currectly being build based on the items in <code>$parent.Activities</code>, also the value is being correctly set as <code>ActivityId</code> but <strong>OptionsCaption is not being added and I can't understand why</strong></p>
  
  <p>Any help would be appreciated. </p>