title: Highcharts load pointStart from JSON. Milliseconds to UTC time?
body: <p>I made a graph with Highcharts which series is loaded from JSON.</p>
  
  <p>I am bit new to handle JSON file though...</p>
  
  <p>I want Highcharts to show date (in formart: YYYY/MM/DD ie.2013/04/01) on label of xAxis.</p>
  
  <p>As far as I know, since I cannot write something like this in JSON,</p>
  
  <pre><code>"pointStart": [Date.UTC(2013, 4, 1)]
  </code></pre>
  
  <p>I wrote milliseconds instead.</p>
  
  <p>My JSON: </p>
  
  <pre><code>[
      {
      "yAxis": 0,
      "type": "column",
      "name": "Y label",
      "data": [0,0,153,179,122,126,120,101,110,95,142,88,82,92,115,101,141,162,0,0,0,0,0,7,6,0,10,0,9,4,56,86,66,61,87,72,74,60,83,74,50,73,61,56,90,78],
      "pointStart": 1364774400000,
      "pointInterval": 86400000
  },{
      "yAxis": 1,
      "type": "line",
      "name": "Y label 2",
      "color": "#AA4643",
      "data": [4980,4572,5554,6147,5268,5221,5263,5084,4906,5000,5198,4777,4790,4549,4158,4294,4891,4689,4432,3925,3708,3723,3623,3831,3787,4353,4809,5046,4989,4815,4315,4556,4502,4725,4537,4540,4654,4367,4589,4874,4837,5032,5046,4633,4561,4576],
      "pointStart": 1364774400000,
      "pointInterval": 86400000
      }
  ]
  </code></pre>
  
  <p>And my javascript:</p>
  
  <pre><code>var options = {
  chart: {
      renderTo: 'container'
  },
  title: {
      text: ''
  },
  xAxis: {
      type: 'datetime',
      dateTimeLabelFormats: {
          day: '%Y/%m/%d'
      },
      labels: {
          rotation: -45,
          align: 'right',
          formatter: function() {
              return Highcharts.dateFormat('%Y/%m/%d', this.x); //this returns invalid date.
          }
      },
      title: {
          text: ''
      }
  },
  
  ...
  
  $.getJSON('test.json', function(data) {
          options.series = data;
          chart = new Highcharts.Chart(options);
  });
  </code></pre>
  
  <p>This results <code>invalid date</code> on xAxis label.</p>
  
  <p>But if I remove this part</p>
  
  <pre><code>formatter: function() {
      return Highcharts.dateFormat('%Y/%m/%d', this.x);
  }
  </code></pre>
  
  <p>returns no error but results like <code>1. Apr</code> which I do not desire to show :(</p>
  
  <p>Any solution to this?</p>
  
  <p>Thank you.</p>