title: Show a "Bar" for zero results with morris.js
body: <p>I'm using <a href="http://morrisjs.github.io/morris.js/" rel="nofollow noreferrer">Morris.js</a> to display data in charts, Id like to show a bar for every option, even if its zero, currently I get this:</p>
  
  <p><a href="https://i.stack.imgur.com/1Q5x9.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1Q5x9.jpg" alt="Current chart:"></a></p>
  
  <p>As you can see the values for 'HIV Instant' for age group 21-25 and 26-30 are 0, how would I show a line (just a thin one) for each result? is this possible with Morris? I've searched the <a href="http://morrisjs.github.io/morris.js/bars.html" rel="nofollow noreferrer">docs</a> for bar charts &amp; searched google &amp; SO but cant find anything? Any help is appreciated. Cheers</p>
  
  <p>Here is the code for generating said chart:</p>
  
  <pre><code>// break up the object
  var age_barParts = [];
  $.each( results_by_age_chart, function(key , val){
      age_barParts.push({
          'test': key,
          'u16': val['u16'],
          '16-20': val['16-20'],
          '21-25': val['21-25'],
          '26-30': val['26-30'],
          '31-49': val['31-49'],
          '50+': val['50+']
      });
  });
  //build the graph
  var age_bar = Morris.Bar({
      element: 'age_bar',
      data: age_barParts,
      xkey: ['test'],
      ykeys: ['u16', '16-20', '21-25', '26-30', '31-49', '50+'],
      labels: ["Under 16s", "16 to 20", "21 to 25", "26 to 30", "31 to 49", "Over 50s"],
      barColors: color_array,
      hideHover: 'auto',
      resize: 'true',
      gridTextSize: 16,
      gridTextColor: '#5cb85c',
      xLabelAngle: '70',
      resize: true,
      padding: 40
  });
  </code></pre>