[1.6.x] Fixed #22392 -- Corrected deployment instructions for Apache 2.4.

Thanks zjcheah at yahoo.com for the report.

Backport of 0f37d2e4c0 from master
[1.6.x] Added RemoteUserMiddleware to middleware reference page.

Backport of 465980d070a33555cdabb4787db50a4e23228de2 from master.
[1.6.x] Added a note regarding django.contrib.auth.authenticate.

Thanks Josh Brown for the suggestion.

Backport of ae5b662796 from master
[1.6.x] Fixed #22453 -- Corrected DoesNotExist message in docs.

Thanks Eugenio Cano-Manuel.

Backport of eefad142dee466c1ead6038fbeec75479b1afead from master
[1.6.x] Fixed #22457 -- Fixed contributing guide w/o github set-up

The published commnand was not working when the user did not have
the git client set-up with the public-key. Changed the contributing
guide to clone it from https instead.

Backport of 28102991172ab931d030412275f926c1b05c688d from master.
[1.6.x] Fixed #22220 -- Added more examples to reverse() documention.

Thanks EvilDMP for the suggestions.

Backport of 030dd4f72c from master
[1.6.x] Fixed #22454 - Changed compatibility warning hint for test runner.

Backport of 214d1e1b0f from master
[1.6.x] Fixed #22471 -- Corrected misprint in i18n docs

Backport of 54d5c37de6572eae57a66339bb38719e681cee82 from master.
[1.6.x] Added some missing items to the 1.6.3 release notes.

Backport of c2b269df6e from master
[1.6.x] Fixed #22473 -- Emphasized that Model.clean() is not called from Model.save().

Backport of b43bbd6d39 from master
[1.6.x] Fixed #22458 -- Added a note about MySQL utf8_unicode_ci collation

Thanks tobami at gmail.com for the report.

Backport of 11ac50b18e from master
[1.6.x] Moved RemoteUserBackend documentation to reference guide.

Backport of 26d118c3fe from master
[1.6.x] Corrected the section identifier for MySQL unicode reference.

Backport of b2514c02e1 from master
[1.6.x] Fixed a remote code execution vulnerabilty in URL reversing.

Thanks Benjamin Bach for the report and initial patch.

This is a security fix; disclosure to follow shortly.

Backport of 8b93b31487d6d3b0fcbbd0498991ea0db9088054 from master
[1.6.x] Prevented leaking the CSRF token through caching.

This is a security fix. Disclosure will follow shortly.

Backport of c083e3815aec23b99833da710eea574e6f2e8566 from master
[1.6.x] Fixed queries that may return unexpected results on MySQL due to typecasting.

This is a security fix. Disclosure will follow shortly.

Backport of 75c0d4ea3ae48970f788c482ee0bd6b29a7f1307 from master
[1.6.x] Added information on resolved security issues to release notes.

Backport of c07f3e60c2d455e36ba4ac339d4283d32bbc3814 from master
[1.6.x] Update for 1.6.3 security release.
[1.6.x] Add missing disclosure information to security archive.
[1.6.x] Fixed #22426 -- Added support old-style d.c.messages format.

Forward ported code from 1.5 that adds backwards compatibility with legacy message length.
See commit 9e7183073f64e541587e8dcfd8bb3ddeb47f8162 for details.

Thanks to Ofir Ovadia for the initial patch.

Backport of f286721f7fdc2202f77a5f4d650d9d0779b86811 from master