Migration to Weblate

[Luis Falcon]

Dear all

As you know, we're migrating to Weblate, and we should be ready for the
transition in a couple of weeks.

Updates:

* Currently, the GNU Health translation project is PUBLIC, that is,
  anyone with a login user at hosted.weblate can update the project and
  its component. Weblate has three different types of access:
        * Public: Anyone can read and modify
        * Restricted : It is still readable by everyone. Only users that
          belong to the project can make changes.
        * Private (discarded): Visible only by selected users. 

  We should choose between "Public" or "Restricted". Probably
  restricted is the best option, but probably "Public" is good too.
  What do you think?

* Documentation: Please make yourself acquainted with the new
  translation environment. Here you can find the documentation:

        https://docs.weblate.org/en/latest/index.html


* I have updated the development version of the GH
  control center (gnuhealth-control) so it can now install the language
  from Weblate instead of our current pootle version. More info here:

        https://lists.gnu.org/archive/html/health-dev/2020-06/msg00010.html

  This version is still at development and is just to test, so please
  don't use it in production!


Suggestions are most welcome!

Luis