title: Webpack hot reload via gulp, publicPath causing issues
body: <p>I can't seem to get the hot reload function to work correctly for me. Whenever I do an update I get the following error messages:</p>
  
  <p><em>Get <a href="http://localhost:9090/cd0492f7657672ef15e4.hot-update.json">http://localhost:9090/cd0492f7657672ef15e4.hot-update.json</a> 404 (Not Found)</em><br>
  <em>[HMR] Cannot apply update. Need to do a full reload!</em><br>
  <em>[HMR] (Probably because of restarting the webpack-dev-server)</em></p>
  
  <p>I am pretty sure this is caused by <code>publicPath: '/js/',</code> in <code>gulpfile.js</code> as when I go to <code>http://localhost:9090/cd0492f7657672ef15e4.hot-update.json</code> I get a 404 but when I go to <code>http://localhost:9090/js/cd0492f7657672ef15e4.hot-update.json</code> I can find the file.</p>
  
  <p>However <code>publicPath: '/js/'</code> is needed for <code>app.js</code> so I have no idea how to fix it, any ideas?</p>
  
  <p><strong>webpack.config.js</strong></p>
  
  <pre><code>var webpack = require('webpack');
  module.exports = {
      cache: true,
      entry: ['webpack/hot/dev-server', './resources/assets/app.js'],
      output: {
          path: __dirname + '/public/js',
          publicPath: '/js/',
          filename: "scripts.js"
      },
      module: {
          loaders: [
              {
                  test: /\.jsx?$/,
                  exclude: /(node_modules|bower_components)/,
                  loader: 'babel'
              }
          ]
      }
  };
  </code></pre>
  
  <p><strong>gulpfile.js</strong></p>
  
  <pre><code>...
  var webpackConfig = require('./webpack.config.js');
  ...
  gulp.task('webpack-dev-server', function(callback) {
      // modify some webpack config options
      var myConfig = Object.create(webpackConfig);
      myConfig.devtool = 'eval';
      myConfig.debug = true;
      myConfig.plugins = [
          new webpack.HotModuleReplacementPlugin()
      ];
  
      // Start a webpack-dev-server
      new webpackDevServer(webpack(myConfig), {
          hot: true,
          stats: {
              colors: true
          },
          publicPath: '/js/',
          proxy: {
              '*': 'http://localhost:8080'
          }
      }).listen(9090, 'localhost', function(err) {
          if (err) throw new gulpUtil.PluginError('webpack-dev-server', err);
      });
  });
  </code></pre>