Improved release notes for ticket #10164

Thanks Aymeric for the suggestions.

refs #10164
Fixed #21078 -- Handled additional bad Accept-Language header
Fixed #19885 -- cleaned up the django.test namespace

* override_settings may now be imported from django.test
* removed Approximate from django.test
* updated documentation for things importable from django.test

Thanks akaariai for the suggestion.
Fixed #17262 -- Refactored tzinfo implementations.

This commit deprecates django.utils.tzinfo in favor of the more recent
django.utils.timezone which was introduced when Django gained support
for time zones.
Refactored code and tests that relied on django.utils.tzinfo.

Refs #17262.
Removed unneeded imports in tests's __init__.py and unified them.
Fixed a little mistake in Django 1.7 release notes
Merge pull request #1607 from Diskun/master

Fixed a little mistake in Django 1.7 release notes
Fixed #21033 -- Fixed uploaded filenames not always being truncated to 255 characters
Fixed #18403 -- Initialized bad_cookies in SimpleCookie

Thanks Stefano Crosta for the report.
Fixed #21057 -- Prevented FileSystemStorage from leaving temporary files.
Fixed #7467 -- Added a template block to override the admin welcome message.

Thanks Jeff Kowalczyk for the suggestion and rctay for the patch.
Fixed #4574 -- Added CSS classes to the admin calendar widget for better control over styling.
Fixed #21075 - Improved doc for calling call_command with arguments.
Fixed #16534 -- Improved ability to customize DiscoverRunner

Added DiscoverRunner.test_suite and .test_runner attributes.

Thanks tomchristie for the suggestion and jcd for the patch.
Fixed #21083 - Fixed spelling in tutorial.

Thanks jimmy.kjaersgaard at gmail.com for the report.
Fixed #20978 -- Made deletion.SET_NULL more friendly for MigrationWriter.serialize.
Made MigrationWriter look for a "deconstruct" attribute on functions.

Refs #20978.
Fixed #20841 -- Added messages to NotImplementedErrors

Thanks joseph at vertstudios.com for the suggestion.
Fixed test that fails when pytz is installed.

pytz' localize() method is the bane of my life.