Add Spanish missing keys. Update Spanish internationalized values to have the word Jenkins instead of Hudson. Changes in translation tool to advise when a file have the Hudson word

Regrettably the CLI client and the CLI server are in the same package, and this doesn't work very well with i18n scheme as we end up having two classes of the same name (and one hides the other in the server.)

So I'm renaming the Messages class on the client, but not the classes itself for compatibility