[Prototype] Step 1: Create "Echo" prototype which echoes message received from UI back to client, without using live broker and modules

[env-tools]

The architecture of the new system is composed of Core Module which exposes Websocket channels to browsers and Functionality-specific modules which process requests routed through core module, return results through messaging and fire event messages asynchronously.

We must implement simple proof of concept which is able to generate message at client (JS) side, process it at core module, route to specific module and get it back to UI, and measure roundtrip time.

As a first step, we mock interfaces with Broker + Modules by simple BlockingQueue, and implement client + websocket + core module.

UI might have a simple text field (message content), text field for module id and "Send" button.
Roundtrip time should be shown for each invocations.
Probably "connect" and "disconnect" buttons should be available in the prototype.