CJ Short methods

Not quite sure, but hey here's a solution for simplifying things and getting rid of procs (if needed)

    def generate_num(n)
      n.times.map { rand(10) }.join
    end
    def generate_char(n)
      n.times.map { ('A'..'Z').to_a.sample }.join
    end

then `generate_default_name` could be simplified to

    def generate_default_name
      "#{generate_num(2)}#{generate_char(3)}"
    end