Failing tests on the 2.3 branch

Ones with reasons

test_binascii: exceptions are strings, not classes, so issubclass() raises an exception; a2b_qp not implemented; a2b_uu has a logic error that makes it fail on the UUencoding of an empty string.

test_StringIO: root cause: .join([unicode, str]) returns str, should be unicode

test_dumbdbm: with very large strings, the value retrieved is incorrect.

test_format: '%d' % '1' works, should raise a TypeError.

test_fileinput: patch in SF.