Some content needs to exist in a non-default language

From Leo's comments on #81:

[Comment](https://github.com/simonwheatley/babble/issues/81#issuecomment-10639151):

> I think this is a good idea, I only propose one change.
>
> With this approach you can not have a post in a secondary language that does not exist in the default language. I dont like this.
>
> Perhaps we could store in what language that post was originally created and then hide the metaboxes in all translations of that post, despite its the original language or not.
>
> What do you think?

and

[Comment](https://github.com/simonwheatley/babble/issues/81#issuecomment-10658064):

> I worked on a project that needed this. The vast majority of the content was created and translated from the default language, but eventually they had some posts that were exclusive to one or other language.
>
> I thought that was reasonable.
>
> I think that its a good approach to set up a primary language for each post, where the terms are associated, and etc.. but I agree with you we can wait to have a better picture of the whole workflow before digging into this

Accordingly, consider this issue parked until we have the translations workflow in place.

Start by reading issue #81 and the referenced translation-workflow discussion. This issue is explicitly parked until that workflow exists; completion would require deciding how posts originating in a non-default language are associated with translations and how the related metaboxes behave.

Written by the indexing model from the issue text.