Sync w/ latest openstack common log.py.

Includes the following updates for openstack-common's log.py:

    Remove code to clear basicConfig root log handlers

    Removes some old Nova specific code to clear out the log handlers
    from Nova's logging basicConfig. This code is arguably Nova specific
    and doesn't really belong in openstack-common's generic logging
    configuration.

    Additionally, This code was actually removing the root logger used
by
    some command line tools and binaries and hiding log messages that
should
    have otherwise gone to the console.

    Fixes LP Bug #1029577.

Change-Id: Ic6a6862e5bc357846bf3202186c7e24622d3bb87

nova/openstack/common/log.py

@@ -357,17 +357,6 @@ def _setup_logging_from_conf(product_name):
         for handler in log_root.handlers:
             logger.addHandler(handler)
 
-    # NOTE(jkoelker) Clear the handlers for the root logger that was setup
-    #                by basicConfig in nova/__init__.py and install the
-    #                NullHandler.
-    root = logging.getLogger()
-    for handler in root.handlers:
-        root.removeHandler(handler)
-    handler = NullHandler()
-    handler.setFormatter(logging.Formatter())
-    root.addHandler(handler)
-
-
 _loggers = {}