Fix the path of PIDFILE for Ubuntu/Debian

The PIDFILE is pointing for `/var/run/redis.pid` but on Ubuntu and Debian it's located at `/var/run/redis/redis-server.pid`.

This misconfiguration creates a bug of restarting `redis-server` service at every Puppet pull because the command `/etc/init.d/redis-server status` checks for the wrong PIDFILE and always return false.