renamed 'USER' variable with 'engine_user' (avoiding to hide already system defined var
renamed 'USER' variable with 'engine_user' (avoiding to hide already system defined var


Former-commit-id: 9bc5c7afc9d31e0bf2e58a3349a40cc3752a9063
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine