polymerx-cli implementation

[LasaleFamine]

This issue will be a to-do list for adding the PolymerX/polymerx-cli:

Files to remove:

• webpack.*

Dependencies to remove:

"devDependencies": {
   ...
    "babel-loader": "7.1.2",
    "babel-plugin-transform-object-rest-spread": "6.26.0",
    "babel-preset-env": "1.6.1",
    "clean-webpack-plugin": "0.1.17",
    "copy-webpack-plugin": "4.2.0",
    "postcss": "6.0.13",
    "postcss-loader": "2.0.8",
    "text-loader": "0.0.1",
    "webpack": "3.8.1",
    "webpack-dev-server": "2.9.3",
    "webpack-merge": "4.1.1",
    "workbox-webpack-plugin": "2.1.0"
	...
  },

More to come.