New example: Distributed task queue

Adds an example of using Kubernetes to build a distributed task queue
using Celery along with a RabbitMQ broker and Flower frontend.

Resolves: #1788

examples/celery-rabbitmq/celery-app-add/celery_conf.py

@@ -0,0 +1,13 @@
+import os
+
+from celery import Celery
+
+# Get Kubernetes-provided address of the broker service
+broker_service_host = os.environ.get('RABBITMQ_SERVICE_SERVICE_HOST')
+
+app = Celery('tasks', broker='amqp://guest@%s//' % broker_service_host, backend='amqp')
+
+@app.task
+def add(x, y):
+    return x + y
+