Enable Object#tap in Ruby 1.8

tap.rb

# Object.tap method for Ruby 1.8 as defined at
# http://ciaranm.wordpress.com/2008/11/30/recursive-lambdas-in-ruby-using-objecttap/
if not Object.respond_to? :tap
  class Object
    def tap
      yield self
      self
    end
  end
end