Add support for AmXYChart.
Add demo for BubbleChart.
Add support for AmAngularGauge, AmBalloon, AmRadarChart, GaugeArrow, GaugeAxis, GaugeBand.
Clean Up
1. Move gen package out of api as it is not gwt compatible.
2. GraphDataItemJSO and SerialDataItemJSO are currently not being used. Revisit later.