For apparmor, create local subdir and ntp stub file.

Recipe assumes /etc/apparmor.d/local/, but ubuntu 10.04 (LTS, still supported) does not use this, and the recipe fails.

This patch uses directory and cookbook_file with not_if guards to create the directory and position an empty local/usr.sbin.ntp file, if they don't already exist.

Patched cookbook has been successfully tested against 10.04 and 14.04.