Go back to default signature method

dm/client.py

@@ -34,8 +34,7 @@ class Client(object):
         self.session = requests.Session()
         self.session.auth = OAuth1(key, client_secret=secret,
                                    resource_owner_key=token,
-                                   resource_owner_secret=token_secret,
-                                   signature_method='PLAINTEXT')
+                                   resource_owner_secret=token_secret)
         self.base_url = base_url
         self.log = logging.getLogger(__name__)