Monkey-patch Chef::Node#role? method so it can search through an array.

role.rb

class Chef
  class Node
    def role?(argument)
      if argument.is_a? Array
        argument.detect {|r| run_list.include? "role[#{r}]" } ? true : false
      else
        argument.include? "role[#{argument}]"
      end
    end
  end
end