title: Webpack 3: Use sass-loader and ExtractTextPlugin doesn't work
body: <p>I've been trying to use the sass-loader in webpack and I follow this instructions -> <a href="https://github.com/webpack-contrib/extract-text-webpack-plugin#extracting-sass-or-less" rel="nofollow noreferrer">https://github.com/webpack-contrib/extract-text-webpack-plugin#extracting-sass-or-less</a> but this not working.</p>
  
  <p><strong>Can anybody help me?</strong></p>
  
  <p><strong>Repository</strong> </p>
  
  <p><a href="https://github.com/gpincheiraa/boolean-html-js-exercises/tree/dev" rel="nofollow noreferrer">https://github.com/gpincheiraa/boolean-html-js-exercises/tree/dev</a></p>
  
  <p><strong>Error</strong></p>
  
  <pre><code>ERROR in   Error: Child compilation failed:
    Module build failed: Error: "extract-text-webpack-plugin" loader is used without the corresponding plugin, refer to https://github.com/webpack/extract-text-webpack-plugin for the usage example
  
    - Error: "extract-text-webpack-plugin" loader is used without the corresponding plugin, refer to https://github.com/webpack/extract-text-webpack-plugin for the usage example
  </code></pre>
  
  <p><strong>Dependencies</strong></p>
  
  <pre><code>node v6.11.1
  npm 5.3.0
  
  ├── babel-cli@6.26.0
  ├── babel-loader@7.1.2
  ├── babel-plugin-transform-class-properties@6.24.1
  ├── babel-polyfill@6.26.0
  ├── babel-preset-es2015@6.24.1
  ├── babel-preset-stage-3@6.24.1
  ├── css-loader@0.28.7
  ├── extract-text-webpack-plugin@3.0.0
  ├── html-loader@0.5.1
  ├── html-webpack-plugin@2.30.1
  ├── markdown-loader@2.0.1
  ├── node-sass@4.5.3
  ├── sass-loader@6.0.6
  ├── style-loader@0.18.2
  ├── webpack@3.5.6
  └── webpack-dev-server@2.7.1
  </code></pre>
  
  <p><strong>webpack.config.js</strong></p>
  
  <pre><code>const HtmlWebpackPlugin = require('html-webpack-plugin');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  
  module.exports = {
      entry: [
        "./index.js"
      ],
      output: {
          path: __dirname + "/dist",
          filename: "index.bundle.js"
      },
      module: {
          rules: [
              { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" },
              { test: /\.md$/, loaders: [ "html-loader", "markdown-loader" ] },
              { test: /\.scss$/,
                use: ExtractTextPlugin.extract({
                    fallback: 'style-loader',
                    use: ['css-loader', 'sass-loader']
                })
              }
          ]
      },
      plugins: [
          new ExtractTextPlugin('style.css'),
          new HtmlWebpackPlugin({
            template: 'index.html',
            inject: 'body'
          })
      ],
      devtool: "eval-source-map",
      devServer: {
          filename: "index.bundle.js",
          contentBase: "./",
          port: 3000,
          publicPath: "/",
          stats: {
              colors: true
          }
      }
  };
  </code></pre>