Modularization of the codebase

[kensongzhu]

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[x] Feature request
[ ] Documentation issue or request
[ ] Support request

## Current behavior

The script only works with ES5 and will hijack global in the browser

## Expected behavior

- Restructure and pack it as **UMD** module (except **Commonjs**). It should be able to be used as **ES6** and **AMD** module. 
- npm package "publishable"

## What is the motivation / use case for changing the behavior?

- Modularization
- Bundle 
- managed as npm package 

## Environment
only on browser side