Tests written for the odd_or_even method

The odd_or_even method is kind of surprising for what it returns
Accept a number and give an answer for Even or Odd

This is now simply doing the one thing with any given number.
Moved odd_or_even to Integer class

We are not using refinements for this, but that is a good research
subject.  We did monkey patch Integer directly.  Now we can use
`odd_or_even` directly on the integer.
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Merge branch 'master' of github.com:atul9/rubylearning56