Better handling of attribute defaults

[vegu]

if you have a ConfigSchema, it has a default, then it creates argparse with a default
so you can't tell if the value passed is actually passed in, or just left blank

There currently is an issue where default's cannot be reasonably determined in a setup that uses schema for cli arguments as well as config data objects.

[egfrank]

Okay pushed again for the apply_argparse changes we were talking about:
f26c6da