Update the JS tooling

* get rid of gulp
* use webpack-dev-server to serve app.js
* express serves static files
* 2 webpack configs: local and production
* for development with backend, websocket URL is injected
* remove unneeded static files

client/server.js

@@ -0,0 +1,88 @@
+var express = require('express');
+var proxy = require('proxy-middleware');
+var httpProxy = require('express-http-proxy');
+var url = require('url');
+
+var app = express();
+
+
+/************************************************************
+ *
+ * Express routes for:
+ *   - app.js
+ *   - index.html
+ *
+ *   Proxy requests to:
+ *     - /api -> :4040/api
+ *
+ ************************************************************/
+
+// Serve application file depending on environment
+app.get('/app.js', function(req, res) {
+  if (process.env.NODE_ENV === 'production') {
+    res.sendFile(__dirname + '/build/app.js');
+  } else {
+    res.redirect('//localhost:4041/build/app.js');
+  }
+});
+
+// Proxy to backend
+
+// HACK need express-http-proxy, because proxy-middleware does
+// not proxy to /api itself
+app.use(httpProxy('localhost:4040', {
+  filter: function(req) {
+    return url.parse(req.url).path === '/api';
+  },
+  forwardPath: function(req) {
+    return url.parse(req.url).path;
+  }
+}));
+
+app.use('/api', proxy('http://localhost:4040/api/'));
+
+// Serve index page
+
+app.use(express.static('build'));
+
+
+/*************************************************************
+ *
+ * Webpack Dev Server
+ *
+ * See: http://webpack.github.io/docs/webpack-dev-server.html
+ *
+ *************************************************************/
+
+if (process.env.NODE_ENV !== 'production') {
+  var webpack = require('webpack');
+  var WebpackDevServer = require('webpack-dev-server');
+  var config = require('./webpack.local.config');
+
+  new WebpackDevServer(webpack(config), {
+    publicPath: config.output.publicPath,
+    hot: true,
+    noInfo: true,
+    historyApiFallback: true,
+    stats: { colors: true }
+  }).listen(4041, 'localhost', function (err, result) {
+    if (err) {
+      console.log(err);
+    }
+  });
+}
+
+
+/******************
+ *
+ * Express server
+ *
+ *****************/
+
+var port = process.env.PORT || 4042;
+var server = app.listen(port, function () {
+  var host = server.address().address;
+  var port = server.address().port;
+
+  console.log('Scope UI listening at http://%s:%s', host, port);
+});