tone down the warning for missing configuration file
tone down the warning for missing configuration file

The warning logged when we can't load a configuration file looks like an
error because it has "Errno" in it. It's not really an error, though, so
log a more gentle message saying that the configuration file does not
exist where we expect to find it.

Change-Id: I30698162615b494f4ed2d23f119309e9fcdf3edd
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/reno