Refactor setup_logging

This change just cleans up the setup_logging function. It was
defined in keystone.common.config and then also exported from
keystone.config. Also, it had extra parameters that were unused.

This takes care of a NOTE (which probably should have been a
TODO) in the code.

Change-Id: I1a46c8974cbd68a5bf708d253adfadc1fdb76dcd
Merge "Refactor setup_logging"