Monkey patch to add postcss-cssnext to create-react-app

package.json

{
  "name": "create-react-app-example",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "postcss-cssnext": "^3.0.2",
    "react": "^16.1.1",
    "react-dom": "^16.1.1",
    "react-scripts": "1.0.17"
  },
  "scripts": {
    "postinstall": "sed -i.bak \"s/\\srequire('postcss-flexbugs-fixes')/require('postcss-cssnext'),require('postcss-flexbugs-fixes')/g\" node_modules/react-scripts/config/webpack.config.dev.js && sed -i.bak \"s/\\srequire('postcss-flexbugs-fixes')/require('postcss-cssnext'),require('postcss-flexbugs-fixes')/g\" node_modules/react-scripts/config/webpack.config.prod.js",
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test --env=jsdom",
    "eject": "react-scripts eject"
  }
}