Homework 8 complete

Completed HW 8.  Will start working on final project later this week.
actually, python "int" is a "long int" -- i.e. it automatically rolls over to a unlimited precision integer -- so only limit is computation time.

But there is a bug -- it reports True for some even numbers::
  In [8]: for i in range(10):
     ...:     print i, __is_prime(i)
     ...:     
  0 False
  1 False
  2 True
  3 True
  4 True
  5 True
  6 True
  7 True
  8 True
  9 False