Replace sprockets/browserify with Webpack (#2617)

* Replace browserify with webpack

* Add react-intl-translations-manager

* Do not minify in development, add offline-plugin for ServiceWorker background cache updates

* Adjust tests and dependencies

* Fix production deployments

* Fix tests

* More optimizations

* Improve travis cache for npm stuff

* Re-run travis

* Add back support for custom.scss as before

* Remove offline-plugin and babili

* Fix issue with Immutable.List().unshift(...values) not working as expected

* Make travis load schema instead of running all migrations in sequence

* Fix missing React import in WarningContainer. Optimize rendering performance by using ImmutablePureComponent instead of
React.PureComponent. ImmutablePureComponent uses Immutable.is() to compare props. Replace dynamic callback bindings in
<UI />

* Add react definitions to places that use JSX

* Add Procfile.dev for running rails, webpack and streaming API at the same time

config/webpack/shared.js

@@ -0,0 +1,59 @@
+// Note: You must restart bin/webpack-dev-server for changes to take effect
+
+/* eslint global-require: 0 */
+/* eslint import/no-dynamic-require: 0 */
+
+const webpack = require('webpack')
+const { basename, dirname, join, relative, resolve } = require('path')
+const { sync } = require('glob')
+const ExtractTextPlugin = require('extract-text-webpack-plugin')
+const ManifestPlugin = require('webpack-manifest-plugin')
+const extname = require('path-complete-extname')
+const { env, paths, publicPath, loadersDir } = require('./configuration.js')
+
+const extensionGlob = `**/*{${paths.extensions.join(',')}}*`
+const packPaths = sync(join(paths.source, paths.entry, extensionGlob))
+
+module.exports = {
+  entry: packPaths.reduce(
+    (map, entry) => {
+      const localMap = map
+      const namespace = relative(join(paths.source, paths.entry), dirname(entry))
+      localMap[join(namespace, basename(entry, extname(entry)))] = resolve(entry)
+      return localMap
+    }, {}
+  ),
+
+  output: {
+    filename: '[name].js',
+    chunkFilename: '[name]-[chunkhash].js',
+    path: resolve(paths.output, paths.entry),
+    publicPath
+  },
+
+  module: {
+    rules: sync(join(loadersDir, '*.js')).map(loader => require(loader))
+  },
+
+  plugins: [
+    new webpack.EnvironmentPlugin(JSON.parse(JSON.stringify(env))),
+    new ExtractTextPlugin(env.NODE_ENV === 'production' ? '[name]-[hash].css' : '[name].css'),
+    new ManifestPlugin({ fileName: paths.manifest, publicPath, writeToFileEmit: true }),
+    new webpack.optimize.CommonsChunkPlugin({
+      name: 'vendor',
+      minChunks: ({ resource }) => /node_modules/.test(resource)
+    })
+  ],
+
+  resolve: {
+    extensions: paths.extensions,
+    modules: [
+      resolve(paths.source),
+      resolve(paths.node_modules)
+    ]
+  },
+
+  resolveLoader: {
+    modules: [paths.node_modules]
+  }
+}