message: Added bubble chart
  Issue
diff: @@ -339,7 +339,7 @@ slide.addChart({TYPE}, {DATA}, {OPTIONS});
  ### Chart Types
  * Chart type can be any one of `pptx.charts`
  -* Currently: `pptx.charts.AREA`, `pptx.charts.BAR`, `pptx.charts.LINE`, `pptx.charts.SCATTER`, `pptx.charts.PIE`, `pptx.charts.DOUGHNUT`
  +* Currently: `pptx.charts.AREA`, `pptx.charts.BAR`, `pptx.charts.BUBBLE`, `pptx.charts.LINE`, `pptx.charts.SCATTER`, `pptx.charts.PIE`, `pptx.charts.DOUGHNUT`
  ### Multi-Type Charts
  * Chart types can be any one of `pptx.charts`, although `pptx.charts.AREA`, `pptx.charts.BAR`, and `pptx.charts.LINE` will give the best results.
  @@ -526,6 +526,15 @@ var dataChartScatter = [
  ];
  slide.addChart( pptx.charts.SCATTER, dataChartScatter, { x:1.0, y:1.0, w:6, h:4 } );
  +// Chart Type: BUBBLE
  +var dataChartBubble = [
  + { name:'X-Axis', values:[1, 2, 3, 4, 5, 6] },
  + { name:'Airplane', values:[33, 20, 51, 65, 71, 75], sizes:[10,10,12,12,15,20] },
  + { name:'Train', values:[99, 88, 77, 89, 99, 99], sizes:[20,20,22,22,25,30] },
  + { name:'Bus', values:[21, 22, 25, 49, 59, 69], sizes:[11,11,13,13,16,21] }
  +];
  +slide.addChart( pptx.charts.BUBBLE, dataChartBubble, { x:1.0, y:1.0, w:6, h:4 } );
  +
  // Chart Type: Multi-Type
  // NOTE: use the same labels for all types
  var labels = ['Q1', 'Q2', 'Q3', 'Q4', 'OT'];
  