Add default rspec options in a .rspec file
Separate the Failable class and spec out into separate files
Ignore the .ruby-version file
Make success and failure class methods on Failable
Include the Monad module within failable_spec.rb

This way the Failable class can be accessed within having to specify the
Monad module as a namespace.
Refactor the Failable example into two
Fix a spelling error
Use polymorphism to elimate the logic from Failable

Factored out the success and failure cases into to separate sub classes.
Not sure this is the final interface yet. I don't like that Failable can
be accidentally instantiated when it is intended as an abstract class.
Need to find out how this should be resolved in Ruby.