(feature) Add environment parameters in the config

[thomaspoignant]

Requirements

Add an environment parameter in the config.
This environment field should be added to all users in the param so we can add rules based on the environment and have the same config file for all your environment.

[thomaspoignant]

While reading this again I have doubts about the strategy to use to handle multiple environments.
Do we want to have multiple files (one per env) or another strategy?