Updated openstack/openstack
Project: openstack/keystone  2ab2c624353067ba0989720414e5cde2d4792bcc
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Sync log module from oslo

This patch sync latest log module from oslo, bases on oslo-incubator
commit f06276bbdabd408549ecefa377b1349b57f5ac82.

DocImpact: Deprecate option log_config in favor of log_config_append.
Change option default_log_levels's default value.

Change-Id: Id2f7cf245499394554f6aa2c8d846cc9e2c2133a