Add ensure-web-ext test job

Change-Id: I72b307e8e0c42faa73511d6b2f8b690cc81d5a94
diff --git a/playbooks/test-ensure-web-ext.yaml b/playbooks/test-ensure-web-ext.yaml
new file mode 100644
index 0000000..5d48e61
--- /dev/null
+++ b/playbooks/test-ensure-web-ext.yaml
@@ -0,0 +1,6 @@
+- hosts: all
+  roles:
+    - ensure-web-ext
+  tasks:
+    - name: Print web ext version
+      command: web-ext --version