Fixed #22315 -- str/bytes mismatch in staticfiles

Previously, `ManifestFilesMixin.read_manifest` failed in Python 3
because `json.loads` accepts `str` not `bytes`.
Fixed #22331 -- Fixed migrations ProjectState to ignore unmanaged models.
Fixed #22322 -- Fixed incorrect explanation of what managed=False does.

refs #14305.

Thanks Adrian Klaver for the report.
Fixed #12030 -- Validate integer field range at the model level.

Thanks to @timgraham for the review.
Add some syncdb deprecation stuff into the deprecation doc
Fixed #22331 -- Made MigrationAutodetector ignore unmanaged models.

This commit reverts 69d4b1c and tackle the issue from a different angle.
Models remain present in the project state, but are now ignored by the
autodetector.
Fixed field deconstruction tests failures introduced by 1506c71a95.

refs #12030.
Fixed #22335 -- Fixed popen_wrapper error on non-English Windows systems.
Merge pull request #2481 from zsiciarz/ticket-22335

Fixed #22335 -- Fixed popen_wrapper error on non-English Windows systems.
Fixed Python 3.4 test failure.
Fixed #22029 -- Removed obsolete advice on registering migrate/syncdb signal handlers.

All signals should now be registered in AppConfig.ready().

Thanks un33k for the report.
Fixed the PostGIS circular imports caused by 1506c71a95.

Thanks to @loic for the help and @timgraham for the review.

refs #12030.
Fixed #22114 -- Stopped adding trailing slashes in URLField.to_python

Thanks coredumperror at gmail.com for the report and Tim Graham
for the review.
Forgotten slash removal in d320863878
Add a useful stacklevel to some RemovedInDjango19Warnings
Skipped a test that errors rather than marked it as an expectedFailure.

The test throws an error which Python 3.4 doesn't seem to catch as an
expectedFailure.

refs 7476d96f83a004d674244aeb7a66289035427396
Fixed a deprecation warning on Python 3.
Fixed #21941 -- Documented the kwargs param of django.conf.urls.url().

Thanks cjerdonek for the report.
Added Python 3.4 support notes.
Fixed a deprecation warning with the HTMLParser safe argument.

refs 6ca6c36f82b97eafeada61384b2e2f1d0587da86