Moved ServerHandler helper class to tests.

It has been only used in the builtin_servers tests since Django 1.4.
Fixed #22167 -- Improved documentation on context processors

Clarified the explanation on the order in which user provided variables
to render_to_response, RequestContext and context processors are
loaded.
Fixed #22266 - quote PK before redirecting away from add_view (django.contrib.admin)
Fixed #15716 - Authentication backends can short-circuit authorization.

Authorization backends can now raise PermissionDenied in "has_perm"
and "has_module_perms" to short-circuit authorization process.
Fixed #21905 -- Add info message if DateField or TimeField use a fixed value
Fix storing of binary fields and unicode textfields for Oracle/Python3
Fixed typo.
Fixed #22625 -- Normalized make_aware/naive errors.

Also added tests for is/make_aware/naive.

Thanks Tom Michaelis for the report.
Optimized make_aware/naive by removing redundant checks. Refs #22625.

Also added tests with pytz and removed misplaced tests.
Added stub release notes for 1.6.6.
Fixed #16245 -- Included traceback in send_robust()'s response

Exceptions from the (receiver, exception) tuples returned by
``send_robust()`` now have always their traceback attached as their
``__traceback__`` argument.
Fixed jenkins breakage, apparently migrations need a models module.

Workaround for now, Andrew will look into it.
Merge pull request #2346 from Markush2010/ticket21905

Fixed #21905 -- Add info message if DateField or TimeField use a fixed value
Fixed #22648 -- Transform.output_type should respect overridden custom_lookup and custom_transform.

Previously, class lookups from the output_type would be used, but any
changes to custom_lookup or custom_transform would be ignored.
Fixed #22019 -- Added Model.objects reference documentation.
Fixed contrib.gis tests breaking in some edge cases.

The tests would error out with an ImproperlyConfigured error
if the user had psycopg installed but not geos.
Thanks to mcgohier for the report.
Fixed #22644 -- Clarified documentation for NamedUrlWizardView
Fixed #22647 -- Documented redirect_field_name keyword argument for user_passes_test.
Fixed #22626 -- Allow BinaryField defaults with SQlite.

Also fixes a slight issue in sqlite3.schema._remake_table where
default values where quoted with "column name" quoting rules.

Reference for quoting: http://www.sqlite.org/lang_expr.html

Thanks Shai Berger for the review. Refs #22424.
Fixed several flake8 errors, including one where a test wouldn't be run