Rename the Array class to be the Enumerable module
Rename #product to #numeric_product to avoid conflicts with Array#product
Add Enumerable#empty?
Add Enumerable#length
Add some tests on Ranges to the Enumerable tests
Fix Enumerable#middle for non-Array objects
Fix Enumerable#occurences for Enumerables that don't implement #each

However, an implementation of #each_with_index is required (as it is in Ruby's
Enumerable mixin).
Alias Enumerable#size to Enumerable#length
Merge branch 'feature/extend-enumerable' into develop
Move String#palindrome? to Enumerable and make it work with other Enumerables
Test Arrays and Ranges in the Enumerable#palindrome? test
Use "item.is_a? Class" instead of "item.class <= Class"
Fix Strings not including the new Enumerable methods
Add Integer#palindrome?
Merge branch 'master' into develop
Use the documentation format for rspec's output
Don't use "should" in test titles
Simplify Enumerable#occurences and Math.primes
Travis: Don't test on JRuby or Rubinius
Refactor a few methods