Replace socket.io with plain WebSocket

Replace socket.io with plain WebSocket using the ws library as it
doesn't really provide any useful tools over plain WebSocket when it
comes to implementing reliable communication that works across
reconnects.  The widespread browser support for WebSocket also means
it has little value to add for the web interface over WebSocket.

clusterctl.js

@@ -1,4 +1,3 @@
-const io = require("socket.io-client");
 const jwt = require("jsonwebtoken");
 const fs = require("fs-extra");
 const yargs = require("yargs");
@@ -315,10 +314,16 @@ commands = new Map([...commands.map(command => [command.name, command])]);
 /**
  * Connector for control connection to master server
  */
-class ControlConnector extends link.SocketIOClientConnector {
+class ControlConnector extends link.WebSocketClientConnector {
+	constructor(url, token) {
+		super(url);
+		this._token = token;
+	}
+
 	register() {
 		console.log("SOCKET | registering control");
 		this.send('register_control', {
+			token: this._token,
 			agent: 'clusterctl',
 			version: version,
 		});
@@ -328,8 +333,7 @@ class ControlConnector extends link.SocketIOClientConnector {
 /**
  * Handles running the control
  *
- * Connects to the master server over the socket.io connection and sends
- * commands to it.
+ * Connects to the master server over WebSocket and sends commands to it.
  */
 class Control extends link.Link {