Git 1.8.4-rc4

As we had to revert two topics at the last minute, let's have
another (hopefully short) round of rc to make sure the final release
will be sound.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Typofix draft release notes to 1.8.4

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git 1.8.4

Signed-off-by: Junio C Hamano <gitster@pobox.com>