Comment 2 for bug 993616

Encountered this indirectly from issue:
https://bugs.launchpad.net/juju/+bug/1052088

If it wasn't for the debug logs, I'd have no idea what valid values are
for juju-origin.

It also appears that when you're doing an LXC deploy, only a subset
of variables is necessary like admin-secret, but not control-bucket (vice vera?).

This is really just standard UNIX convention, there ought to be an
annotated config file that describes everything, and in what context
that they're valid in. A man page would nice too, also standard
convention.

Maybe we can generate these from the unit tests? That would streamline
maintenance as these annotated config files have a habit of falling behind.