Add Elixir tutorials

[Maikon]

Hey everyone 😃

This is an initial draft for adding the Elixir tutorials and to get some thoughts/feedback from the community.

The roadmap is the following:

• [x] Introduction to Elixir and Functional Programming
• [x] Installing Elixir
• [x] Interactive Elixir (Introduction to IEx)
• [x] Elixir Basics (data types/structures)
• [x] Expressive Elixir - Thinking in Patterns
• [ ] Expressive Elixir - Functions and the Pipe operator
• [ ] Recursion
• [ ] Introduction to Mix (starting a new project)
• [ ] Testing

I also wanted to explain my approach with these tutorials which is based on personal experience, both at teaching at Codebar as well as my own apprentices at 8th Light. It's also influenced by this blog post. The goal is to have small tutorials that cover one new concept at a time. This enables the student to achieve small wins and reinforce the feeling of achievement more frequently.

What would be nice is if we can think of an exercise which can be broken down into sections where each section is covered in one of the above lessons and at the end the student ends up building a nice little project that would otherwise be too big to complete in one lesson.

Any feedback on any of the above would be great 😃

[barisbalic]

This is cool, definitely keep it up.

[KimberleyCook]

I'm going to close this PR as it's very old, I'd still very much be interested in an Elixir tutorial for our blog though in our tech section https://medium.com/the-codelog