Restart samba instead of reloading it.

In some cases samba needs a restart instead of a reload to
have changes take effect.  In particular nmbd reload does
not do the right thing when you change the samba netbios
name.

This probably fixes a long standing bug where samba name changes
don't take effect until after a reboot.

This probably introduces a new behavior where changing certain
samba settings causes a restart when it isn't strictly needed.