DockerClient.secrets should be a @property

Signed-off-by: Joffrey F <joffrey@docker.com>

docker/client.py

@@ -119,6 +119,7 @@ class DockerClient(object):
         """
         return PluginCollection(client=self)
 
+    @property
     def secrets(self):
         """
         An object for managing secrets on the server. See the