title: Webpack dev server - exporting .CSS file on change
body: <p>I'm building .SASS into one .CSS file using webpack, but it only exports the file when I "webpack" in the terminal. When I run "webpack-dev-server" it sees the changes but doesn't generate/change the output .CSS file: </p>
  
  <pre><code>var webpack = require('webpack');
  var path = require('path');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  const autoprefixer = require('autoprefixer');
  
  module.exports = {
      devtool: 'inline-source-map',
      entry: [
          'webpack-dev-server/client?http://127.0.0.1:8080/',
          'webpack/hot/only-dev-server',
          './src'
      ],
      output: {
          path: path.join(__dirname, 'public'),
          filename: 'bundle.js',  // this exports the final .js file
          publicPath: '/public'
      },
      module: {
          loaders: [
              {
                  test: /\.jsx?$/,
                  exclude: /node_modules/,
                  loaders: ['react-hot', 'babel?presets[]=react,presets[]=es2015']
              },
  
             {
                  test: /\.scss$/, loader: ExtractTextPlugin.extract('css!sass') // this loads SASS
              }
  
          ]
      },
  
      plugins: [
          new webpack.HotModuleReplacementPlugin(),
          new webpack.NoErrorsPlugin(),
          new ExtractTextPlugin("./bundle.css") //this exports the CSS file
      ],
  
      resolve: {
          modulesDirectories: ['node_modules', 'src'],
          extensions: ['', '.js', '.scss'],
          root: [path.join(__dirname, './src')]
      }
  };
  </code></pre>
  
  <p>It works completely fine with just "webpack" but I wonder how to make it generate the file using the server, so that I don't have to type in the terminal every time I make a change to the styles.</p>