Handle case where os_auth_token is set to ''

Properly handle case (as in CLI) where os_auth_token is
set, but to an empty string.

Change-Id: I7e96bf22e2a91e0e3ec783b406fd05e4138860c8

ceilometerclient/client.py

@@ -74,7 +74,7 @@ def get_client(api_version, **kwargs):
         }
         _ksclient = _get_ksclient(**ks_kwargs)
         token = ((lambda: kwargs.get('os_auth_token'))
-                 if 'os_auth_token' in kwargs
+                 if kwargs.get('os_auth_token')
                  else (lambda: _ksclient.auth_token))
 
         endpoint = kwargs.get('ceilometer_url') or \