def build_option(args={})
      options << Option.new(args.merge(group: self))
      options.last
    end
def build_option(args={})
      options << Option.new(args.merge(group: self))
      options.last
    end
Initialize a new Option to this group. Takes the same arguments as Opto::Option
 @param [Hash] option_definition
 @return [Opto::Option]