Clean up pep8 E711 violations

Fixed E711 errors
All ignores are to be removed in the next sequence of patches

Change-Id: Id9bcdfa276d30639dc6d16b8ce6db19101153fcd
diff --git a/tempest/common/rest_client.py b/tempest/common/rest_client.py
index 32dd124..7e3084b 100644
--- a/tempest/common/rest_client.py
+++ b/tempest/common/rest_client.py
@@ -143,7 +143,7 @@
                     tenant_id = auth_data['token']['tenant']['id']
                     break
 
-            if mgmt_url == None:
+            if mgmt_url is None:
                 raise exceptions.EndpointNotFound(service)
 
             if service == 'network':
@@ -186,7 +186,7 @@
             self._set_auth()
 
         self.http_obj = httplib2.Http()
-        if headers == None:
+        if headers is None:
             headers = {}
         headers['X-Auth-Token'] = self.token