Added AMD/UMD support
Added AMD/UMD support

Used the template from https://github.com/umdjs/umd/blob/master/returnExports.js
jiangzhonghui/Chart.Scatter,dima117/Chart.Scatter,freeman-lab/Chart.Scatter,freeman-lab/Chart.Scatter,dima117/Chart.Scatter,jiangzhonghui/Chart.Scatter