title: How to display tooltips or legends on plotBands?
body: <p>I would like to have tooltips or legends on the gauge bands. I draw the bands like these:</p>
  
  <pre><code>plotBands: [{
                  from: 0,
                  to: 10,
                  color: '#55BF3B'
              }, {
                  from: 10,
                  to: 20,
                  color: '#DDDF0D'
              }]
  </code></pre>
  
  <p>I would like to see tooltips on mouseover on the bands. </p>
  
  <p>Or the other solution I would like to have is showing legends for each band with the regarding color. There is the option for legends for points but not for bands.</p>
  
  <p>Is there any option like <code>showInLegend:true</code> for plotBands? Or any other solution to get these?</p>