git-commit: pass explicit path to git-diff-files.
git-commit: pass explicit path to git-diff-files.

When running "git commit" with explicit path arguments, allow it to
take directory name.  This makes "git commit Documentation/" to commit
everything that is changed under Documentation/ directory.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git