Revert "client.logger.warning wrongly used in migrations"

This is a partial revert of the previous patch. The inline setup of
the logger ends up causing issues when this is consumed by other
libraries that want control over the logger.

Closes-Bug: #1697452

This reverts commit 9a27201416.

Change-Id: I1d61d4952aef1039e72a2aac629cb13a6a15d7b2

novaclient/v2/client.py

@@ -183,11 +183,7 @@ class Client(object):
         self.server_external_events = \
             server_external_events.ServerExternalEventManager(self)
 
-        if not logger:
-            logger = logging.getLogger(__name__)
-            if not logger.handlers:
-                logger.addHandler(logging.StreamHandler())
-        self.logger = logger
+        self.logger = logger or logging.getLogger(__name__)
 
         # Add in any extensions...
         if extensions: