Implement WebI2C polyfill for node backend

[dynamis]

Overview Description (Goal of this issue)

We want WebI2C polyfill for node backend to make WebI2C testable/usable on other devices. This make API consideration easy and fast. Also, many other devices including production embedded devices can share same code and ecosystem.

• [CHIRIMEN] - [current WebI2C polyfill] - [browser applications]
• [node.js] - [i2c module] - [new WebI2C polyfill] - [node applications]
• [node.js] - [i2c module] - [local i2c server] - (web socket?) - [another WebI2C polyfill for Firefox] - [browser applications]

Action Itemc (Requirements to close this issue)

• [ ] select node version (6.x or later?)
• [ ] select node module for I2C
  • https://www.npmjs.com/package/i2c ?
• [ ] implement WebI2C polyfill on node
• [ ] implement WebI2C polyfill on normal Firefox with local node backend

see also: #188

[dynamis]

create repo with new implementation: #195

[dynamis]

DONE by tadfmac: https://github.com/chirimen-oh/chirimen-raspi3