future proofing is good, but...

since print() was made a function in py3, i can predict at some point
that return will be made a func as well. sure, good.
but "return()" *currently* returns an empty tuple. We want to
explicitly return None for testing purposes.

aif/system/__init__.py

@@ -18,4 +18,4 @@ class Sys(object):
         self.tz.apply()
         self.user.writeConf()
         self.services.apply()
-        return()
+        return(None)