title: Google Charts: How I can change "Choose a value..." in controlType: CategoryFilter of ControlWrapper
body: <p>I need know how change "Choose a value..." in controlType: CategoryFilter of ControlWrapper</p>
  
  <p>Example:</p>
  
  <pre class="lang-js prettyprint-override"><code> // Define a category picker control for the Gender column    
  var categoryPicker = new google.visualization.ControlWrapper({
            'controlType': 'CategoryFilter',
            'containerId': 'control2',
            'options': {
          'filterColumnLabel': 'Sexo',
        'ui': {
            'labelStacking': 'vertical',
                'allowTyping': false,
                'allowMultiple': false,
              }
            },
        'state': {'selectedValues': ['']} // this don't solve my problem
          }); 
  </code></pre>
  
  <p>This show me one select box like this:<br>
  [ Choose a value...]<br>
  [ Man ]<br>
  [ Woman ]</p>
  
  <p>And I need this:<br>
  [ Choose sex...]<br>
  [ Man ]<br>
  [ Woman ]</p>
  
  <p>Thanks!</p>