title: highchart x axis not showing correct date labels
body: <p>i am using highchart and loading a json dynamically.
  json provides me the date time series and its value</p>
  
  <p>The chart is being created and the tooltip is showing the correct value 
  only the x-axis labels are not shown correctly.</p>
  
  <pre><code>  $(function () {
          $('#container').highcharts({
              xAxis: {
                  type: 'datetime',
                  dateTimeLabelFormats: {
                      day: '%e of %b'
                  }
              },
  
              series: [{
                  data: [
  ["2013-09-15 08:44:37",19.8],
  ["2013-09-18 08:47:37",18.4],
  ["2013-09-19 08:50:37",18.3],
  ["2013-09-20 08:53:37",18.1]
      ],
                  //pointStart: Date.UTC(2010, 0, 1),
                  pointInterval: 24 * 3600 * 1000 // one day
              }]
          });
      });
  </code></pre>
  
  <p>live plunkr : <a href="http://plnkr.co/edit/TfcJVPpqu6ZM2LywKmO5?p=preview" rel="nofollow">http://plnkr.co/edit/TfcJVPpqu6ZM2LywKmO5?p=preview</a></p>
  
  <p>Kindly assist. Thanks</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>I have updated the post and the plunkr with the correct dates</p>