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.
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.