Fixed occasional selenium test failure on Jenkins with Chrome 36+.

Previously find_element_by_id('id_password') on the next line failed with
NoSuchElementException and selenium.page_source was
<html xmlns="http://www.w3.org/1999/xhtml"><head></head><body></body></html>.

Possibly related: https://code.google.com/p/selenium/issues/detail?id=1969.
Move my bio to "Past team members" section whilst I'm inactive.
Fixed #23474 -- Prevented migrating backwards from unapplying the wrong migrations.
Fixed #23486 -- Corrected makemigrations output in tutorial 1.

Thanks nmarler for the report.
Fixed #19463 -- Added UUIDField

Uses native support in postgres, and char(32) on other backends.
Fixed #23492 -- Restored F.__deepcopy__.

This reverts commit 3a66035107a640c4905f0a5f247a45f32dbe16d7.
A regression test was also added.
Added 1.7.1 release notes for refs #23492.
Fixed typo in docs/internals/roles.txt and added words to spelling_wordlist.