Add a cloud-config based install test

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

tests/assets/cloud_config_install_test/cloud-config.yml

@@ -0,0 +1,27 @@
+#cloud-config
+write_files:
+- path: /opt/install
+  permissions: "0755"
+  content: |
+    #!/bin/sh
+    set -ex
+    echo "running" > /var/log/ros-install.log
+    system-docker exec console ros install -i rancher/os:v1.0.1 -d /dev/vda --append "rancher.password=rancher" -f --no-reboot --debug >> /var/log/install.log 2>&1
+    echo "done" > /var/log/ros-install.log
+ssh_authorized_keys:
+  - ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC85w9stZyiLQp/DkVO6fqwiShYcj1ClKdtCqgHtf+PLpJkFReSFu8y21y+ev09gsSMRRrjF7yt0pUHV6zncQhVeqsZtgc5WbELY2DOYUGmRn/CCvPbXovoBrQjSorqlBmpuPwsStYLr92Xn+VVsMNSUIegHY22DphGbDKG85vrKB8HxUxGIDxFBds/uE8FhSy+xsoyT/jUZDK6pgq2HnGl6D81ViIlKecpOpWlW3B+fea99ADNyZNVvDzbHE5pcI3VRw8u59WmpWOUgT6qacNVACl8GqpBvQk8sw7O/X9DSZHCKafeD9G5k+GYbAUz92fKWrx/lOXfUXPS3+c8dRIF
+rancher:
+  services:
+    ros-install:
+      image: alpine
+      entrypoint: /usr/bin/ros entrypoint
+      command: /opt/install
+      labels:
+        io.rancher.os.scope: system
+        io.rancher.os.after: console
+      uts: host
+      privileged: true
+      volumes:
+        - /var/log:/var/log
+      volumes_from:
+        - all-volumes