[1.7.x] Removed duplicate "Deprecated in Django A.B" text in docs.

sphinx 1.2+ adds this text itself.

Backport of 7f4347b176 from master
[1.7.x] Fixed #20815 -- Don't enforce unbuffered I/O on Python 3.

No test because this code is already deprecated (part of FastCGI support).

Backport of 5836a577 from master
[1.7.x] Fixed #22772 -- Defer wizard temporary files deletion.

Backport of e2112edd9a from master
[1.7.x] Fixed #22436: More careful checking on method ref'ce serialization
[1.7.x] Fixed #22749: Making SQL management commands migration aware.