Add local copy of commit-msg hook

Add local copy of commit-msg hook

To avoid using untrusted network to download code, copy the
relevant file to the repo and adapt "make gitconfig" to copy
from there.

Change-Id: I21f0b58d59250aa5d795cf289267ad93bd8d74db
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/73
Reviewed-by: Uwe Hermann <uwe@hermann-uwe.de>
Tested-by: build bot (Jenkins)