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

bin/webpack-dev-server

@@ -0,0 +1,33 @@
+#!/usr/bin/env ruby
+$stdout.sync = true
+
+require "shellwords"
+require "yaml"
+
+ENV["RAILS_ENV"] ||= "development"
+RAILS_ENV = ENV["RAILS_ENV"]
+
+ENV["NODE_ENV"] ||= RAILS_ENV
+NODE_ENV = ENV["NODE_ENV"]
+
+APP_PATH    = File.expand_path("../", __dir__)
+CONFIG_PATH = File.join(APP_PATH, "config/webpack/paths.yml")
+
+begin
+  paths = YAML.load(File.read(CONFIG_PATH))[NODE_ENV]
+
+  NODE_MODULES_PATH   = File.join(APP_PATH.shellescape, paths["node_modules"])
+  WEBPACK_CONFIG_PATH = File.join(APP_PATH.shellescape, paths["config"])
+
+  WEBPACK_BIN       = "#{NODE_MODULES_PATH}/.bin/webpack-dev-server"
+  DEV_SERVER_CONFIG = "#{WEBPACK_CONFIG_PATH}/development.server.js"
+rescue Errno::ENOENT, NoMethodError
+  puts "Configuration not found in config/webpacker/paths.yml."
+  puts "Please run bundle exec rails webpacker:install to install webpacker"
+  exit!
+end
+
+Dir.chdir(APP_PATH) do
+  exec "NODE_PATH=#{NODE_MODULES_PATH} #{WEBPACK_BIN} --progress --color " \
+    "--config #{DEV_SERVER_CONFIG} #{ARGV.join(" ")}"
+end