Use dhcp client / avahi after NM (#75)

* Use dhcp client / avahi after NM

* Store networkmanager

* Add default connection

* cleanup

* cleanup lease

* faster boot

* Cleanup

* Fix permission

buildroot-external/rootfs-overlay/usr/lib/systemd/system/var-lib-NetworkManager.mount

@@ -0,0 +1,14 @@
+[Unit]
+Description=NetworkManager persistent data
+Requires=mnt-data.mount
+After=mnt-data.mount
+Before=NetworkManager.service
+
+[Mount]
+What=/mnt/overlay/var/lib/NetworkManager
+Where=/var/lib/NetworkManager
+Type=none
+Options=bind
+
+[Install]
+WantedBy=hassos-bind.target