Create /person/info endpoint

[SimonLab]

Now that the auth service returns a jwt on authenticate, we want to be able to fetch the information about a person based on this jwt.

• Create the /person/info endpoint where the header of the request will contain the jwt.

[SimonLab]

The request on /person/info must contains the the Authorization field in the headers: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Authorization

We can create a plug which will verify the jwt exist and is valid in the headers.
This plug can then be used on the endpoints where authorisation is necessary:
https://hexdocs.pm/phoenix/plug.html

[SimonLab]

At the moment the only information returned for a person is her email.
To be able to link other data to this person from other application we need to have a unique reference to this user.
We can for now use the id of the person from Postgres and we can later on find a more unique value to represent this person (cid?)