Added Singleton and Observer pattern

Observer Pattern:
  Example is fans following the news of a popstar.  The fans register with the
  popstar receive news.  One fan unregisters and the rest receive further news.
  This shows the how pattern works, through registrations, notification and
  unregistering.

Singleton:
  Both Singleton and Singleton with exception are the same.  They show how to
  create an instance of an object so that only no or one may exist at any given
  time.