Translated Articles support

[Sergio Xalambrí]

Is your feature request related to a problem? Please describe.
Contentz should support the idea that an article may be translated and let define if it was translated from or it has been translated to.

Describe the solution you'd like
In the original article I want to add something like this:

translatedTo:
  - lang: en
    path: /articles/en/my-post
  - lang: br
    path: /articles/es/my-post

In the translated articles something like this:

translatedFrom:
  lang: es
  path: /articles/my-post

This should be rendered in the UI of the articles to show the possible translations or the original one