[publican-list] Overriding settings in publican.cfg

[Jared Smith]

Would it be possible to make it so that we can override the settings
from publican.cfg?

In the older versions of Publican which were build on make files, it was
easy to do things such as:

CONDITION=red-pill make pdf-en-US
CONDITION=blue-pill make pdf-en-US

Now that Publican no longer uses make files, it's difficult to easily
override the settings in publican.cfg.  The two options I've though of
are:

1) allow environment variables to override the settings in publican.cfg

 or

2) Allow Publican to look for another configuration file via another
command-line switch, such as publican --config foo.cfg build
--formats=html-single --langs=en-US

Thoughts?  Ideas?  

--
Jared Smith