Trivial: remove None as a redundant argument to dict.get()

`dict.get()` returns `None` by default, if a key wasn't found.
Removing `None` as second argument to avoid redundancy.

Change-Id: I898219110206e9c49348f9a36f07b5ba1766f0f1

ceilometerclient/client.py

@@ -410,7 +410,7 @@ def _construct_http_client(**kwargs):
                                                          'publicURL')),
             region_name=kwargs.pop('region_name', None),
             user_agent=kwargs.pop('user_agent', 'python-ceilometerclient'),
-            auth=kwargs.get('auth', None),
+            auth=kwargs.get('auth'),
             timings=kwargs.pop('timings', None),
             **kwargs)
     else: