Add support for forward/reverse DNS range split

- Allow for explicit reverse RFC1918 lookups with unbound_reverse_zones
- Add tests, similar to NSD ones
- Wait for network to be online before starting (fixes AETHER-1041)
- Multiplatform support

Change-Id: I385aec6f766b45a9db595d2f8af5ed8fe0dde2ca
diff --git a/files/network_online.conf b/files/network_online.conf
new file mode 100644
index 0000000..5d61ced
--- /dev/null
+++ b/files/network_online.conf
@@ -0,0 +1,5 @@
+# SPDX-FileCopyrightText: © 2020 Open Networking Foundation <support@opennetworking.org>
+# SPDX-License-Identifier: Apache-2.0
+[Unit]
+After=network-online.target
+Wants=network-online.target