Keep track of which configuration file a group of settings is in to
try to report that as a detail for user settings.
Track settings from the command line separately from settings in the
configuration files.
It is possible that the configuration file details can be wrong if a
group appears in more than one file. We can be more accurate with this
after we have the backend driver feature implemented, but since most
deployments use a single file so this should be relatively useful.
Change-Id: I04ce72dbc5f676296acfeafc13169177ad815350
Signed-off-by: Doug Hellmann <doug@doughellmann.com>