API: cannot update user

[j.jaffeux (Joffrey Jaffeux)]

Your Content-Type is wrong:

Yours: Content-Type: text/html; charset=utf-8
Mine: Content-Type: application/json; charset=utf-8

Try to use this URL:

https://disc.uaar.it/users/m.redaelli.json?api_key=***&api_username=m.redaelli