better defaults for "models"

requests/models.py

@@ -76,6 +76,7 @@ class Request(object):
         #: Dictionary or byte of querystring data to attach to the
         #: :class:`Request <Request>`.
         self.params = None
+        self.params = dict(params or [])
 
         #: True if :class:`Request <Request>` is part of a redirect chain (disables history
         #: and HTTPError storage).
@@ -440,7 +441,7 @@ class Response(object):
         self.request = None
 
         #: A dictionary of Cookies the server sent back.
-        self.cookies = None
+        self.cookies = {}
 
         #: Dictionary of configurations for this request.
         self.config = None