Remove module name shadowing in sas.system.__init__

[pkienzle]

The name shadowing in sas/system/__init__.py such as from .env import env is confusing. With this style you cannot access the module without doing tricks like import sys; env = sys.modules['sas.system.env'].

[lucas-wilkins]

That's kind of the point of doing it.

[pkienzle]

From past experience this will cause difficulties for future maintainers.