Completing debian LSB start/stop script

When you exec 'update-rc.d' or 'insserv', you obtain:

```
insserv: Script redis6379 is broken: incomplete LSB comment.
insserv: missing `Required-Start:' entry: please add even if empty.
insserv: missing `Required-Stop:'  entry: please add even if empty.
```

I have only added "Required-Start:" and "Required-Stop:" entries