Adopt oslo.log default_log_levels

oslo logging complains that:

"Option verbose from group DEFAULT is deprecated for removal. Its
value may be silently ignored in the future."

Switch to using default_log_levels instead.

Change-Id: Ibddb8b379753193624d1a3df1cf2c53018c0a62b

neutron/common/config.py

@@ -259,6 +259,9 @@ def setup_logging():
     """Sets up the logging options for a log with supplied name."""
     product_name = "neutron"
     logging.setup(cfg.CONF, product_name)
+    # We use the oslo.log default log levels and add only the extra levels
+    # that Neutron needs.
+    logging.set_defaults(default_log_levels=logging.get_default_log_levels())
     LOG.info(_LI("Logging enabled!"))
     LOG.info(_LI("%(prog)s version %(version)s"),
              {'prog': sys.argv[0],

neutron/tests/etc/neutron.conf

@@ -1,6 +1,6 @@
 [DEFAULT]
 # Show more verbose log output (sets INFO log level output)
-verbose = True
+default_log_levels = neutron=INFO
 
 # Show debugging output in logs (sets DEBUG log level output)
 debug = False