Build Docker Image

[adyromantika]

Build Docker image to push to https://hub.docker.com/r/loomnetwork/phaser-sdk-demo/

Also includes a Linux fix for:

ERROR in ./src/states/Game.js
Module not found: Error: Can't resolve '../simpleContract' in '/app/src/states'
 @ ./src/states/Game.js 3:0-47
 @ ./src/main.js
 @ multi babel-polyfill ./src/main.js

ERROR in ./src/main.js
Module not found: Error: Can't resolve './simpleContract' in '/app/src'
 @ ./src/main.js 4:0-46
 @ multi babel-polyfill ./src/main.js

[Mc01]

Appreciated 👍