Backport of b8f78823 from master

Backport of a3253827 from master

mysqlclient 1.3.7 fixes the test failures caused by 1.3.6.

Backport of 2514e044 from master

Backport of ce4914ea from master

Backport of a8f05f40 from master

Backport of 97886252 from master

Thanks Josh, Anssi, and Carl for reviews and advice.

Backport of 91a431f4 from master

Instead of using DjangoJSONEncoder, use base_field's value_to_string().

Note this means the serialization of e.g. IntegerRangeField now has
strings for lower and upper, so use to_python when they came back in
(same behaviour as ArrayField, hopefully, from where I also got the
set_attributes_from_name function).

Backport of 86d9b10d and
8a842148 from master

Use the DjangoJSONEncoder so that datetime and date are encoded
appropriately.

Backport of 2926559c from master

Backport of cc8c02fa from master

Backport of 4a9c32f5 from master

Backport of cb322921 from master

Backport of 34669ea6 from master

This is consistent with the behavior of Django 1.7.x and earlier.

Backport of d3e3703a from master

Backport of 4c593eaa from master

Backport of e0de82c9 from master

Thanks to Jamie Matthews for finding and explaining the bug.

Backport of 46085737 from master

A non-upgraded app is one that retains South migrations in the
`migrations` module and doesn't introduce Django migrations.

psycopg2 now publishes binary wheel files for Windows
so you can install it using pip.

Backport of bc6eaca3 from master

This fixes a regression from refs #25496.

Backport of 1155843a from master

Thanks Simon Charette for review.

This only happens if USE_TZ = False and pytz is installed (perhaps not
the most logical combination, but who am I to jugde?)

Refs #23714 which essentially fixed the same problem when USE_TZ = True.

Thanks Florian and Carl for insisting until I wrote a complete patch.

Backport of 1014ba02 from master

To improve consistency, sample URL names that had underscores
in them now use dashes instead. That excludes URL names that
have some relation to the code, such as those generated by
the admin.

Thanks guettli for reporting this.

Backport of 16794721 from master

Backport of 81006b96 from master

Backport of ac750dbb from master

Backport of f98126a0 from master

Backport of 99c58c27 from master

Backport of d49b36e4 from master

Backport of 4dea29ec from master

Backport of 4373eac9 from master

Backport of a10cbbbc from master

Backport of cdb17dcb from master

Backport of b67502fb from master

Backport of ad67fcdf from master

Backport of a1721664 from master

This works at least as far back as Django 1.6 according to the test
added in refs #10870.

Backport of e19bd086 from master

Backport of 81b55fb9 from master