Fixed #22254 -- Noted the requirement of calling django.setup() when running

Thanks Peter Landry for the report.
Revert "Fixed #15179 -- middlewares not applied for test client login()"

This reverts commit 4fdd51b73240bf9c8d9472fcc45df699f0714755.

See the ticket for concerns with this implementation; it will be revisited.
Added dates to release notes of today's release.
Added stub release notes for 1.6.5.
Fixed #22523 -- Clarified pytz requirement.

Thanks z for the report and timo for the proposal.
Removed bogus, ineffective 'U' flag from codecs.open() call.
Use the new implementation of `six.with_metaclass`.

No more `NewBase` horrors.

Thanks to bendavis78 for his work on merging this into six.
Fixed #22447 -- Make sure custom model bases can be migrated.

Thanks to cdestigter for the report.
Fixed #19195 -- Allow explicit ordering by a relation source field.

Thanks to chrisedgemon for the report and shaib and akaariai for the review.
Amended documentation.