[fix] Networking config fixes + 18.04 changes

* Add code to allow 18.04 to use Network Manager
* Disable ipv6 on all interfaces to prevent multicast traffic on sniffing interface (revisit later)
* Rename and modify checksum disable script for 18.04 compatibility

Fixes #387
Fixes #413

setup/install_scripts/99-so-checksum-offload-disable

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+if [[ "$DEVICE_IFACE" != "ens33" && "$DEVICE_IFACE" != *"docker"* ]]; then
+	for i in rx tx sg tso ufo gso gro lro; do
+		ethtool -K "$DEVICE_IFACE" "$i" off;
+  	done
+	ip link set dev "$DEVICE_IFACE" arp off multicast off allmulticast off
+fi