Readme love

I was in the process of better understanding jumpup to propose some refactorings and realized that the README could be improved. So I thought it would be better to do that before going crazy and proposing a whole lot of code changes

It can still be improved but here's lots of :heart: :heart: :heart: :heart: :heart: for the readme.

@maurogeorge @thiagogabriel Here's a link to the final version so you guys can read it https://github.com/Helabs/jumpup/tree/fr-readme-tweaks#jumpup

If you are interested on understanding what has been changed, I recommend looking at the commit messages as the diff will be really messed up :smile: 
@fgrehm I vote to keep this here, it is like optional. I think it is a good way to spread the good practice.