parse http address given through command line

use flag package for command line argument parsing

read standard input

show the data in the page itself

read one file with bufio

template variables

Use template

write more messages on a time interval

write message asynchronously using goroutine

Created a separate function to be used as a goroutine.

Receive messages through websocket and display

- Client side HTML & JavaScript to receive a `hello` message

- In the client JavaScript, WebSocket connection object is
  created and an event handler is registered for `onmessage`
  event.  The handler fuction write the message to the
  console (To see the message, open the console in debug window).

- In the server, HTTP handler write a `hello` message to websocket.
  Normal HTTP request is upgraded to websocket using the
  Gorilla websocket package.

- URL origin check is disabled.  This is required as the HTML is
  not served from the same URL origin.  This can be changed later.