Added: simple app.js - server application based on socket.io; it can handle clients connections and disconnections; on each connection server sends a 'greeting' message to client.
Added: index.html - a simple page - once it opened, it automatically connect itself to a server and receives greeting message; after 5 seconds cliend page sends 'disconnect' to a server.
Added: package.json by analogy on socket.io; now we can do 'npm install' to get all necessary files.

 Closes #1