support for Spanish shift character set & fix bugs related to LF CR

I added one feature and fixed one bug:

1. added support for the Spanish characters defined in shift character set.  Added the additional characters and wrote positive and negative tests around conditions.

2. fixed a bug where LF and CR would not encode due to how chars were being pulled from string - switched from string.chars.each which would see "\n" as "\" and "n" and changed to Ruby 1.9 preferred str.each_char which appropriately pulls these escaped characters.

Thanks!