log at INFO level in default log file.
Allow to override default level with LOG_ROOT_LEVEL env variable. Default log dir is now ./logs
Prochaines maintenances programmées: lundi 03/06, lundi 01/07, lundi 05/08
Pour plus d'informations: https://doc-si.inria.fr/display/SU/Gitlab
Allow to override default level with LOG_ROOT_LEVEL env variable. Default log dir is now ./logs