Fixed test failures with Oracle when pytz isn't installed.

Thanks Shai Berger for the report.
Clarified when triagers should close tickets as needsinfo.

https://groups.google.com/d/msg/django-developers/dyldP9kFADc/rHTlRBVEP8MJ
Fix #19664 -- Illegal Characters In Session Key Give Fatal Error On File Backend Only
Fixed test failure introduced in 1927bf7c91.
Fixed #15961 -- Modified ModelAdmin to allow for custom search methods.

This adds a get_search_results method that users can override to
provide custom search strategies.

Thanks to Daniele Procida for help with the docs.
Fix test failure introduced by 980ae2ab29.
Merge pull request #1166 from bbenko/ticket_15961

Fixed #15961 -- Added get_search_results to ModelAdmin
Merge pull request #1178 from bmispelon/master

Fix for test failure introduced by 980ae2a.
Fixed #20183 - Clarified docs assumption that certain objects exist in database.

Thanks Tomasz Jaskowski for the patch.
Made 2d309a70 compatible with Python 3.
Added some links in /docs/intro/overview.txt

Thanks Claes Ström for the patch.
Fixed #16330 -- added --pks option in dumpdata command

Thanks to guettli for the initial ticket and patch, with additional work
from mehmetakyuz and Kevin Brolly.
Fixed #20459 - Improved example for setting HTTP header fields.

Thanks Jérémie Blaser.
Changed API to disable ATOMIC_REQUESTS per view.

A decorator is easier to apply to CBVs. Backwards compatibility isn't an
issue here, except for people running on a recent clone of master.

Fixed a few minor problems in the transactions docs while I was there.
Fixed fixtures testing failure

The failure was caused by generating the same warning from two tests.
The second time the same warning was raised it was swallowed by the
"once" simplefilter of warnings.
Lower the max length for a test field so that it works on MySQL.
Fix typo in redirect view docs
Fixed #20449 - Corrected test sensitivity to current working dir.
Fixed #20437 - marked a test-runner test as expected-fail under certain conditions.
Merge pull request #1181 from aaugustin/better-api-to-disable-atomic-requests

Changed API to disable ATOMIC_REQUESTS per view.