Make NullLogger more logger like
Make NullLogger more logger like

eventlet.wsgi.server is adaptive to dealing with the named log
argument being either a file like or a log like [1], but message
handling is a more direct pass through if it's a log like.

Since all we want to do is make eventlet's logging it a noop - it's
easy to provide either interface!

1. https://github.com/eventlet/eventlet/blob/4d2cdc/eventlet/wsgi.py#L246

Change-Id: I2d792176c96931eafb3f140e6653ba8b31eda429

notmyname/swift,matthewoliver/swift,smerritt/swift,tipabu/swift,hurricanerix/swift,swiftstack/swift,openstack/swift,nadeemsyed/swift,clayg/swift,hurricanerix/swift,openstack/swift,smerritt/swift,notmyname/swift,openstack/swift,psachin/swift,hurricanerix/swift,nadeemsyed/swift,tipabu/swift,psachin/swift,clayg/swift,notmyname/swift,swiftstack/swift,redbo/swift,smerritt/swift,swiftstack/swift,tipabu/swift,clayg/swift,hurricanerix/swift,matthewoliver/swift,openstack/swift,nadeemsyed/swift,smerritt/swift,clayg/swift,matthewoliver/swift,redbo/swift,nadeemsyed/swift,psachin/swift,matthewoliver/swift,psachin/swift,notmyname/swift,tipabu/swift