title: set time for flags
body: <p>Helo!
  I created flag for my chart:</p>
  
  <pre><code>type : 'flags',
      showInLegend: false,
      data : [{
          x : Date.UTC(2012, 11, 02),
          title : '!',
          text : 'bla-bla-bla'
      }]
  </code></pre>
  
  <p>How set date and time for x? Now I set only date <code>Date.UTC(2012, 11, 02)</code></p>