title: Different major tick format in Chart.js
body: <p>I'd like to make regular tick format HH:mm and major ones (on day begin) - MMM D.</p>
  
  <p>My codepen <a href="https://codepen.io/zzmaster/pen/OvNdLe" rel="nofollow noreferrer">https://codepen.io/zzmaster/pen/OvNdLe</a></p>
  
  <pre><code>var options = {
      scales: {
          xAxes: [{
              type: 'time',
              time: {
                  unit: 'hour',
                  unitStepSize: 1,
                  displayFormats: {
                      'hour': 'HH:mm',
                      'day': 'MMM D HH:mm'
                  },
              },
              ticks:{
                  maxTicksLimit: 10,
                  major: {
                      unit: 'day',
                      fontColor: 'red',
                      unitStepSize: 1,
                      displayFormats: {
                          'day': 'MMM D HH:mm',
                          'hour': 'MMM D'
                      },
                  },
              },
          }],
  
          yAxes: [{
              scaleLabel: {
                  display: true,
                  labelString: 'Loading'
              },
          }],
      },
  
  };
  </code></pre>
  
  <p>Looks like displayFormats ignored for major ticks? And I generally don't understand what is the reason of using multiple entries under displayFormats, on which conditions will be used hour or day format? I see no difference in output ticks.. </p>