Add a possibility to handle `The token has an invalid signature` error on creating relayedServer

## Actual Behavior
```
const RelayedServer = require('hyco-websocket').relayedServer;
const wsServer = new RelayedServer({
server: ...,
token: () => WebSocket.createRelayToken(...),
});
```
If token is invalid the following raw error appears in log `at WebSocketClient.failHandshake (C:\Projects\IDEXX\CornerstoneCloud\infra\scripts\websocket-port-bridge\node_modules\hyco-websocket\node_modules\websocket\lib\WebSocketClient.js:339:32)`

## Expected Behavior
Should be able to handle this error in client code.
The issue is in `HybridConnectionsWebSocketServer.js` module (lines 258-260). Can we just add a line `server.emit('error', event);` in `client.on('connectFailed'...` event

## Versions
- OS platform and version: Microsoft Windows 8.1 Pro
- Node Version: v10.9.0
- NPM package version or commit ID: 1.0.5