Trivial git script fixups

Fix permissions, and add trivial "reset" and "add" scripts.

The "reset" script just resets the index back to head, while the "add"
script is just a crutch for people used to do "cvs add".

git-add-script

@@ -0,0 +1,2 @@
+#!/bin/sh
+git-update-cache --add "$@"