[1.5.x] Fixed #20286 - Typo in static files docs.

Thanks bmispelon.

Backport of f71fdf83a8 from master
[1.5.x] Fixed #20285 - Added missing commas in translation docs.

Thanks cody.j.b.scott@

Backport of 9f7b277d2e from master
[1.5.x] Fixed #20270 -- Fixed error in AjaxResponseMixin documentation

Backport of 73c26f0c95 from master.
[1.5.x] Fixed #20307 -- Word repeated in tutorial.

Replaced "the the" in the tutorial with "the".

Backport of f17aa99 from master.
[1.5.x] Fixed the reusable apps docs to use a rst file extension for the README and follow PEP8 a bit more.

Backport of 949b4e94588e73067f64b5b6d22e569a105baaf7 from master.
[1.5.x] Fixed a rST bug in the README template in the reusable apps docs.

Backport of db394e6ab2c1d3d53b8b8d691e995d0c3584b944 from master.
[1.5.x] Updated Transifex links to the Django project

Translations for the Django framework are now hosted on the
django-core Transifex project, and the django project is only
dedicated to a team-only hub project.
Backport of 8f7276b782 from master.
[1.5.x] Fixed #19252 -- Added support for wheel packages.

Backport from master (a5becad9094e5c5403b692b9a7b3a6ffaabf64a3).

Signed-off-by: Jannis Leidel <jannis@leidel.info>
[1.5.x] Fixed #20309 -- admin.py is not automatically created in Django 1.5
[1.5.x] Fixed test failures introduced in a5becad9094e5c5403b692b9a7b3a6ffaabf64a3.

Backport of 780fa48f5fb81b2f0f58de95167abff84a6149aa from master
[1.5.x] Fixed #20305 - Added include for polls/static to MANIFEST.in in tutorial.

Thanks monuszko for the report.

Backport of 86d3079d57 from master
[1.5.x] Fixed #20274 - Added some clarifying section headings in the test docs.

Backport of e886808994 from master
[1.5.x] Fixed #20177 - Corrected docs for django.test.utils.setup_test_environment.

Thanks vlad.london.uk@ for the report.

Backport of bc02a963db from master
[1.5.x] Fixed #20354 -- `makemessages` no longer crashes with `UnicodeDecodeError`

Handle the `UnicodeDecodeError` exception, send a warning to `stdout` with the
file name and location, and continue processing other files.
Backport of 99a6f0e77 from master.
[1.5.x] [py3] Stopped iterating on exceptions. Refs #20025.

Backport of 86b4ac66 from master.
[1.5.x] Fixed #20025 -- Pointed to a MySQLdb fork for Python 3.

Made a few minor compatibility adjustments.

Backport of e81e319f from master.
[1.5.x] Fixed #20385 -- Typo in files docs.

Backport of bdd2857 from master.