Maximum and Minimum monoids

[Gabriel Gonzalez]

I am definitely in favor of adding "semigroups" to the platform if drops 
the containers dependency.  Optionally, we could then fix the Monoid 
instance for Maybe so that it has a proper semigroup context and we 
wouldn't have to use the Option type.  I would be happy with that 
solution.  However, if we do that then rename the types to "Max" and 
"Min" instead of "Maximum and "Minimum", since "Maybe (Max a)" is long 
enough as it is.