Using standard flow and confidential (client_id/client_secret) access.

test_full_login() might be a good entry point to understand the authentication
flow.

How to test this with keycloak:

* Create a new client using url http://<your-local-hostname>:8080
* Set Access Type to "confidential" with standard flow enabled
* Get client_id & client_secret from the "Credentials" tab
* Enable the oauth2 cube to your project
* In all-in-one.conf set oauth2-enabled=yes,
  oauth2-server-url=https://keycloak/auth/realms/master,
  oauth2-client-id=<client_id>, oauth2-client-secret=<client_secret>
* Start your instance, go to login page and click on "Log in with Oauth2"