Allow non-root RTNet Users

non-root-rtnet

Add the user to the xenomai group : 
```bash
user -a -G xenomai student
```

Remove sudo passwd for rtnet operations : 

```
sudo visudo
```

```
xenomai ALL=(root) NOPASSWD:/sbin/insmod
xenomai ALL=(root) NOPASSWD:/sbin/rmmod
xenomai ALL=(root) NOPASSWD:/sbin/modprobe
xenomai ALL=(root) NOPASSWD:/usr/bin/service
xenomai ALL=(root) NOPASSWD:/usr/sbin/service
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtcfg
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtifconfig
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtiwconfig
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtnet
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtping
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/rtroute
xenomai ALL=(root) NOPASSWD:/usr/local/rtnet/sbin/tdmacfg
```