Webpack Plugin Config for Bootstrap 4

webpack-plugin-config-bootstrap-4

Took me 10 minutes to find how to configure Webpack's plugin system to leverage Bootstrap 4. 
Also see my other Gist for [installing and configuring Bootstrap 4](https://gist.github.com/chrisalexander55/81f3d5db057fbcbd74d62d488adbca8a).

```
plugins: [
      new Webpack.ProvidePlugin({
        $: 'jquery',
        jQuery: 'jquery',
        'window.jQuery': 'jquery',
        Popper: ['popper.js', 'default'],
        // In case you imported plugins individually, you must also require them here:
        Alert: "exports-loader?Alert!bootstrap/js/dist/alert",
        Button: "exports-loader?Button!bootstrap/js/dist/button",
        Carousel: "exports-loader?Carousel!bootstrap/js/dist/carousel",
        Collapse: "exports-loader?Collapse!bootstrap/js/dist/collapse",
        Dropdown: "exports-loader?Dropdown!bootstrap/js/dist/dropdown",
        Modal: "exports-loader?Modal!bootstrap/js/dist/modal",
        Popover: "exports-loader?Popover!bootstrap/js/dist/popover",
        Scrollspy: "exports-loader?Scrollspy!bootstrap/js/dist/scrollspy",
        Tab: "exports-loader?Tab!bootstrap/js/dist/tab",
        Tooltip: "exports-loader?Tooltip!bootstrap/js/dist/tooltip",
        Util: "exports-loader?Util!bootstrap/js/dist/util",
      })
    ]
```