Added Spanish ToWords Translation

[thunsaker]

I see that you have a WIP #149 modifying the way ToWords works. If you'd like for me update this PR once those changes are finalized I'd be more than happy to update my code.

[MehdiK]

Thanks a lot for writing this and even more so for acknowledging the need for an update based on #149. That's already merged in and cleans up things fairly well. So I'd appreciate if you could please update your work. Please rebase and force push up. We really prefer clean flat commit tree.

[MehdiK]

Please move Theory to the top.

[MehdiK]

@bangoker thanks. You can pull this code down on your local repo, add your commits and suggestions on top and push a new PR on your fork and we can take it from there. Or @thunsaker could give you access to his fork so you can directly work on that together! Just throwing it out there.

[thunsaker]

@bangoker thanks for the review, I'll make appropriate edits when I get a chance to pull in the latest code.

[thunsaker]

@MehdiK changes should be good to go now. I have rebased and forced merged as requested.

I have translated and prepared the code for ToOrdinalWords on a separate branch, since it seems that it was not ready at this time. My implementation of the INumberToWordsConverter is throwing the default NotImplementedException().

[MehdiK]

Thanks a lot for the contribution. It's merged now. I made a few minor changes. Please review.

[MehdiK]

Thanks for the contribution. This is now available on NuGet in v1.20.2.