Localize ComputerCraft for es_ES

[daelvn]

es_ES: Español de España (Castellano) I created a .lang file for es_ES, it's my native language, so I thought I could do it. Although untested, it should work fine, just as en_US works.

[JakobDev]

dan200 doesn't want other languages than English in the main mod. See #5

[SquidDev]

@Wilma456 Dan's changed his mind on that (https://github.com/dan200/ComputerCraft/issues/294#issuecomment-328358222), so we're all good.

I would probably accept PR's for built in localisations now.

[JakobDev]

@SquidDev Thank you. I have not see this. If dan200 accept this PR, I will make a PR for German.

[scollovati]

Thank you! If this PR is accepted, I can create a PR for Italian translation.

[thatcraniumguy]

Can one of the admins verify this patch?