Remove keystone from default_log_levels default

"keystone=INFO" was in the default_log_levels. This made it
more difficult than necessary to debug the Keystone server,
since you can set debug=True but then the keystone logging
level is overridden and you get no debug output for keystone.

"keystone=INFO" may have been in the default_log_levels because
of the auth_token middleware, but this has been moved to
python-keystoneclient now and the logging config for the
python APIs is done differently.

Closes-Bug: 1245629

Change-Id: Ifc4187188f2be2fc876893e9b75e062f0dfcce97
Remove unused import

Remove unused import in openstack/common/db/sqlalchemy/session.py

Change-Id: Ia89d749f698a9bee71f70fbb7e723a0131bfccfe
Merge "Remove keystone from default_log_levels default"
Merge "Remove unused import"