Legend does not reload when chart is updated.

[henriquecf]

Hello. I noticed that the legend does not update when chart changes. Not sure if this is intended but I solved this with a simple addition to updateChart:

updateChart: function(){
    var chart = this.get('chart');
    var data = this.get('data');
    var redraw = ChartDataUpdater.create({
      data: data,
      chart: chart
    }).updateByType();

    if (redraw) {
      this.willDestroyElement();
      this.didInsertElement();
    } else {
      chart.update();
    }

    if (this.get('legend')) {
      this.$().parent().children('[class$=legend]').remove();
      var legend = chart.generateLegend();
      this.$().parent().append(legend);
    }
  }

If you agree I can make a test and send a pull request.

[aomran]

@henriquecf this looks good.