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.
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.
Fixed #22634 -- Changed Session and SessionStore to be easily extendable

Introduced abstract base model for Session, and properties enabling
the developer to override session model class used by session store
and the session store class used by the model.