Support Auth0 authentication

[La0]

Required by #8

As we have a backend, we can create an Auth0 app using Mozilla-IAM scopes.
Auth0 has a nice doc for generic Python backends

We'll need to add several endpoints:

• /v2/auth/login that redirects the user to an Auth0 url for starting the login process
• /v2/auth/logout that terminates the current Auth0 session

The frontend will also need to receive the callback from the Auth0 signin process and react accordingly.

Protected endpoints will then be able to check a Json Web Token, and check the users scopes (as specified in the doc).

[La0]

I'll work on that when priorities are set by @sylvestre, as this is my cup of 🍵 .

[harshsahu97]

Should I work on this issue?

[marco-c]

This is not an easy issue to start with.

[harshsahu97]

I had implemented the Oauth2 using FLASK-dance in my flask app so i thought I can do this. is there any other issue you can suggest to a beginner?

[marco-c]

Issues marked by the good-first-bug label: https://github.com/mozilla/code-coverage/issues?q=is%3Aissue+is%3Aopen+label%3Agood-first-bug.