JWT authentication for API

[Dynnammo]

Since we want to provide a public endpoint for the API to work, it'll be great to implement a JWT authentication.

Documentation worse useful :

• https://auth0.com/blog/ruby-authentication-secure-rack-apps-with-jwt/
• https://github.com/crystal-community/jwt
• https://jwt.io/introduction/

[armandfardeau]

FYI: https://github.com/Kong/kong

Documented informations : https://docs.konghq.com/gateway/latest/get-started/key-authentication/