Update init.sh as per @systemofapwne recommendation

Solve https://github.com/Fmstrat/samba-domain/issues/11

init.sh

@@ -72,6 +72,7 @@ appSetup () {
 			" /etc/samba/smb.conf
 		sed -i "s/LOCALDC/${URDOMAIN}DC/g" /etc/samba/smb.conf
 		if [[ $DNSFORWARDER != "NONE" ]]; then
+			sed -i "/dns forwarder/d" /etc/samba/smb.conf
 			sed -i "/\[global\]/a \
 				\\\tdns forwarder = ${DNSFORWARDER}\
 				" /etc/samba/smb.conf