Merge client into next (#1709)

* Merge client
* Add linting script
* Rename serve to start:development
* Move error harmonization and handling to network layer
* Show Comment Stream
* Added initial test

scripts/test.js

@@ -0,0 +1,29 @@
+"use strict";
+
+// Do this as the first thing so that any code reading it knows the right env.
+process.env.BABEL_ENV = "test";
+process.env.NODE_ENV = "test";
+process.env.PUBLIC_URL = "";
+
+// Makes the script crash on unhandled rejections instead of silently
+// ignoring them. In the future, promise rejections that are not handled will
+// terminate the Node.js process with a non-zero exit code.
+process.on("unhandledRejection", err => {
+  throw err;
+});
+
+// Ensure environment variables are read.
+require("../config/env");
+
+const paths = require("../config/paths");
+
+const jest = require("jest");
+let argv = process.argv.slice(2);
+
+// Watch unless on CI or in coverage mode
+if (!process.env.CI && argv.indexOf("--coverage") < 0) {
+  argv.push("--watch");
+  argv.push("--config", paths.appJestConfig);
+}
+
+jest.run(argv);