[frontend] Update seafile-editor to 0.1.5 and clean code

frontend/config/server.js

@@ -0,0 +1,24 @@
+'use strict';
+// https://github.com/webpack/webpack-dev-server/blob/master/examples/api/simple/server.js
+
+var Webpack = require('webpack')
+var WebpackDevServer = require('webpack-dev-server')
+var config = require('./webpack.config.dev')
+
+const compiler = Webpack(config);
+const devServerOptions = Object.assign({}, config.devServer, {
+  stats: {
+    colors: true
+  }
+});
+
+console.log('Dev server options:', devServerOptions);
+
+const server = new WebpackDevServer(compiler, devServerOptions);
+server.listen(3000, '0.0.0.0', function (err, result) {
+  if (err) {
+    console.log(err)
+  }
+
+  console.log('Listening at 0.0.0.0:3000')
+})