allow to init some user from environment variable to init some users without using the UI

[StudioEtrange]

allow to init some user from environment variable to init some users without using the UI
it is very confortable when we want to fully automatize ownfoil deployment without any humain intervention

using environment variable
USER_ADMIN_NAME
USER_ADMIN_PASSWORD
to create/update an admin user

using environment variable
USER_GUEST_NAME
USER_GUEST_PASSWORD
to create/update a regular user

[StudioEtrange]

Anybody ? :)

[a1ex4]

Yes this is definitely something I want to merge, but there are problems with the code, all the user management code should be in the auth module, not in the main app.
Also the code to add an user is duplicated, the auth module should be refactored to separate a function that can be reused.