sync log from oslo

5fef5a8105 allow keeping of existing loggers with fileConfig
fb8075a19d Add amqp=WARN,qpid=WARN to default_log_levels
4654a5d247 Don't override default value for eventlet.wsgi.server logging
41ddd7a975 _get_log_file_path explictly return, when logfile/logdire unset
e12e6b45f8 Make openstack.common.log Python 3 compatible
572cfecb4d Make Messages unicode before hitting logging
3243cdfbe9 python3: handle module moves in log

DocImpact

Change-Id: I3f58066c6d18477ec7cfcfd610c71baae9b2e21f