Add ensure-genmanifest role

Change-Id: Ifebf9da8cd8eeaa9cec621e490064a0f935ddbe0
diff --git a/roles/ensure-genmanifest/defaults/main.yaml b/roles/ensure-genmanifest/defaults/main.yaml
new file mode 100644
index 0000000..a17151d
--- /dev/null
+++ b/roles/ensure-genmanifest/defaults/main.yaml
@@ -0,0 +1,2 @@
+---
+genmanifest_version: latest