Add initial Packer definitions

Copy over the Packer definitions from ONOS since we've been asked to set
up the builders the same way initially.

Change-Id: I8c6e3cad05e4d4341ac58498d36810dac06f687f
Signed-off-by: Linux Foundation Administrators <collab-it+onlab@linuxfoundation.org>
diff --git a/packer/vars/cloud-env.json.example b/packer/vars/cloud-env.json.example
new file mode 100644
index 0000000..dc1c08f
--- /dev/null
+++ b/packer/vars/cloud-env.json.example
@@ -0,0 +1,3 @@
+{
+  "subnet_id": "subnet-NNNNNNNN"
+}