Fixed #17431 -- Added send_mail() method to PasswordResetForm.

Credits for the initial patch go to ejucovy;
big thanks to Tim Graham for the review.
Fixed #22770 -- Removed create_superuser from post_migrate signals.

Moved logic to syncdb command for backwards compatibility.
Fixed #22801 -- Added 'www.' to diveintopython.net links
Fixed #22798 -- `pluralize()` now adds plural_suffix for any `1 < d < 2`

Thanks Odd_Bloke for the report.
Fixed #22780 -- Checked that LOCALE_PATHS is really a tuple
Fixed #22680 --  I/O operation on closed file.

This patch is two-fold; first it ensure that Django does close everything in
request.FILES at the end of the request and secondly the storage system should
no longer close any files during save, it's up to the caller to handle that --
or let Django close the files at the end of the request.
Removed an unused local variable, fixes a flake8 error