title: Webpack is not compiling new files into bundle
body: <p>I'm running webpack-dev-server and it keeps serving old files, any ideas? The new bundle still has the old files.</p>
  
  <p>When I run webpack it compiles the new files into a new bundle</p>
  
  <p>config:</p>
  
  <pre><code>module.exports = {
    context: __dirname + "/app",
    entry: "./main.js",
    output: {
      path: __dirname + "/dist",
      filename: "bundle.js"
    },
    devtool: "#source-map",
    module: {
      loaders: [
        // Transpile any JavaScript file:
        {test: /\.js$/, exclude: /node_modules/, loader: 'babel-loader'}
      ]
    },
    resolve: {
      // you can now require('file') instead of require('file.js')
      extensions: ['', '.js', '.json']
    }
  }
  </code></pre>