Show repo languages

[lourot]

For each repos we should see the languages. Right now our DB contains only the main language but I believe it is possible to get all languages from the GitHub API. If not, I remember these projects caught my eyes:

• https://www.wappalyzer.com/
• https://github.com/github/linguist
• https://github.com/src-d/enry

Also it should be possible for a project to define additional technologies in its .ghuser.io.json (described in #3) like "react", "docker". So next to the languages/techs there should be a [+] button leading you to the documentation on how to add technologies to your project.