Revert "Fix for the issue https://github.com/kennethreitz/requests/issues/1280"

This reverts commit ca0aea640d.

requests/sessions.py

@@ -251,8 +251,7 @@ class Session(SessionRedirectMixin):
         hooks=None,
         stream=None,
         verify=None,
-        cert=None,
-        return_response=True):
+        cert=None):
         """Constructs a :class:`Request <Request>`, prepares it and sends it.
         Returns :class:`Response <Response>` object.
 
@@ -340,9 +339,6 @@ class Session(SessionRedirectMixin):
         req.cookies = cookies
         req.hooks = hooks
 
-	if not return_response:
-	  return req
-	
         # Prepare the Request.
         prep = req.prepare()