Address review comments.

enqueue/enqueue-bundle/0.4/etc/packages/test/enqueue.yaml

@@ -0,0 +1,6 @@
+enqueue:
+    transport:
+        default: 'null'
+        'null': ~
+    client:
+        traceable_producer: true

enqueue/enqueue-bundle/0.4/manifest.json

@@ -0,0 +1,8 @@
+{
+    "bundles": {
+        "Enqueue\\Bundle\\EnqueueBundle": ["all"]
+    },
+    "copy-from-recipe": {
+        "etc/": "%ETC_DIR%/"
+    }
+}