title: AmCharts Value axis not starting at Zero
body: <p>I have a AmCharts serial chart with some columns representing numeric values. Depending on those values, sometimes one of the axes "unsticks" from the ground,  <a href="https://i.stack.imgur.com/ccSeL.png" rel="nofollow noreferrer">making a weird effect</a>. I have unsuccessfully tried to set the property valueAxis.minimum to zero. </p>
  
  <p>Is there a way to force a valueAxis to start from zero?</p>
  
  <pre><code>    AmCharts.makeChart("chartdiv", {
          "type": "serial",
          "synchronizeGrid": true,
          "valueAxes": 
              [{
                  "minimum": 0,
                  // ...
              }]
          // ...
      });
  </code></pre>