Remove hard coded attributes in Text Element

[LagTag]

This PR should resolve #28 and add the currently hard coded attributes for the FB. I have kept the default value of 4 for max_lines in case any legacy code was relying on that.

  label = Zebra::Zpl::Label.new(
        :width         => 800,
        :length        => 800,
        :print_speed   => 6,
        :print_density => 5,
        :copies        => 1
      )

 label_fed_number = Zebra::Zpl::Text.new(
        :data           => ("FEDERAL RN#90630 ONT. REG.# 34333"),
        :position       => [200, 600],
        :justification  => Zebra::Zpl::Justification::LEFT,
        :font_size      => Zebra::Zpl::FontSize::SIZE_2,
        :width          => 200,
        :max_lines      => 3,
        :line_spacing   => 3,
        :hanging_indent => 20
      )
label << label_fed_number
label.dump_contents
>>^XA^LL800^LH0,0^LS10^PW800^PR6^FWN^CF0,22^CI28^FO200,600^FB800,3,3,L,20^FDFEDERAL RN#90630 ONT. REG.# 34333^FS^PQ1^XZ