tools/refresh.sh: Now runs make savedefconfig before copying the new defconfig...

tools/refresh.sh: Now runs make savedefconfig before copying the new defconfig file in place;  Also, added a new option --defaults.  Since the number of defaults that you now have to answer is so large, the option lets you just accept the default values.  So it works just like --slilent but still prompts you for the decision to save or discard the new defconfig file.