Basic countdown. Defaulted to 3000 seconds.

- TODO : Should be available as independent command. It should be
  countdown-node. We will have more such countdown command. Like
countdown-lisp, countdown-c, countdown-c++ etc
- TODO : Allow commandline arguments to change the countdown duration.
- TODO : Prompt user to provide duration if not provided in commandline
- TODO : Use the best practices of every language.