add missing os import for config tests
add missing os import for config tests

spulec/moto,william-richard/moto,spulec/moto,william-richard/moto,spulec/moto,william-richard/moto,spulec/moto,spulec/moto,william-richard/moto,william-richard/moto,spulec/moto,william-richard/moto