Add new instal-docker script

install-docker.sh

+#!/bin/sh
+#
+# This script helps us to prepare a Docker host for the build system
+#
+# It is used with Docker Machine to install Docker, plus addons
+#
+# See --engine-install-url at docker-machine create --help
+
+set -e
+
+run() {
+  (set -x; "$@")
+}
+
+echo "Installing Docker via get.docker.com"
+run curl -LsS https://get.docker.com -o /tmp/get-docker.sh
+run sh /tmp/get-docker.sh
+
+echo "Installing QEMU and helpers"
+run sudo apt-get update
+run sudo apt-get install -y qemu-user-static binfmt-support