Building the repo structure

[marcosvital]

Hi, everyone!

I just started to organize a 'courses' folder, so anyone willing to contribute with courseware can add it there. Please comment here (and/or send pull requests) if you have any suggestions on how the material should be organized inside the repository. Keep in mind that, in the future, this repo should have a friendly and easy to use website, so the way we organize the courses files should also reflect that.

I'm working on a first short course, that could work out as a simple model for contributors and as a short and easy R course, and I'll add it as soon as a finish it.