Re-add resume to not break existing apps

as requested by Cory Benfield

requests/status_codes.py

@@ -30,7 +30,8 @@ _codes = {
     305: ('use_proxy',),
     306: ('switch_proxy',),
     307: ('temporary_redirect', 'temporary_moved', 'temporary'),
-    308: ('permanent_redirect',),
+    308: ('permanent_redirect',
+          'resume_incomplete', 'resume',), # These 2 to be removed in 3.0
 
     # Client Error.
     400: ('bad_request', 'bad'),