Include ref log detail in commit, reset, etc.

When updating a ref at the direction of the user include a reason why
head was changed as part of the ref log (assuming it was enabled).

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-reset.sh

@@ -48,7 +48,7 @@ then
 else
 	rm -f "$GIT_DIR/ORIG_HEAD"
 fi
-git-update-ref HEAD "$rev"
+git-update-ref -m "reset $reset_type $@" HEAD "$rev"
 
 case "$reset_type" in
 --hard )