Move Linux client & common packages into a public repo.

cmd/relaynode/docker/run.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+# Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+set -e
+redo-ifchange build
+docker run --cap-add=NET_ADMIN \
+	--device=/dev/net/tun:/dev/net/tun \
+	-it tailscale