Added missing .pot files, translated hardcoded strings in modules and completed Spanish translation

There are lost of little changes in this pull request. I've added sme .pot files that were not being generated. I also went over most of the strings in the modules and templates and translated in the same way I saw you were doing it in other places. I also fixed some English strings and completed the Spanish translation.

There are lots of changes here. Next time if you want I can make lots of small commits.

I've tested practically all of the translations on my local Zotonic installation.