Moved ServerHandler helper class to tests.

It has been only used in the builtin_servers tests since Django 1.4.
Fixed #22216 -- Added Form.non_field_errors to form API doc.
Fixed #21977 -- Deprecated SimpleTestCase.urls
Removed casting to bool just before negation.
Fixed #21084 -- Used proxy model's content type for admin log entries.
Fixed #21084 -- Used proxy model's content type for admin log entries.

(the previous commit included only the test)
Added missing request parameter to get_current_site().
Fixed #22405 -- Fixed string error in models/queries docs.
Fixed #9535 -- Added a reference guide for file upload classes.
Fixed some spelling issues in docs.
Added Python 3.4 to list of supported version in docs/intro/install.txt
Fixed #16205 -- Added an installation for Windows.
Refs #21230 -- removed direct settings manipulation from signed cookies tests
Fixed #13408 -- Deprecated silent unpacking exception passing in for template tag.

Thanks peterbe for the suggestion.
Fixed small typo in django-admin.txt

The word 'by' seemed to be missing from the first line of the compilemessages command.
Noted that pip is included with Python 3.4 in Windows install guide.

Thanks CHI Cheng.
Used more specific test assertions.
Fixed #21553 -- Ensured unusable database connections get closed.
Fixed #22401 -- Deprecated regular expression parsing of initial SQL in favor of installing sqlparse.
Fixed #22343 -- Disallowed select_for_update in autocommit mode

The ticket was originally about two failing tests, which are
fixed by putting their queries in transactions.

Thanks Tim Graham for the report, Aymeric Augustin for the fix,
and Simon Charette, Tim Graham & Loïc Bistuer for review.