PHPUnit 5.7 Not Passing Env Variable

[ajquick]

Unfortunately PHP testing on 5.6 has been allowed to fail through Travis as it is not correctly passing our hidden variable $USPS_USERID through to the phpunit configuration. This appears to be a problem with phphunit 5, as the other versions do not suffer from this problem. If anyone knows how to fix this without explicitly defining the variable in the phpunit.xml file and making our USPS api credentials public.