Adding schema for redis cluster.

examples/guestbook/redis.jinja

@@ -1,5 +1,5 @@
 {% set REDIS_PORT = 6379 %}
-{% set WORKERS = properties['workers'] or 2 %}
+{% set WORKERS = properties['workers'] %}
 
 resources:
 - name: redis-master

examples/guestbook/redis.jinja.schema

@@ -0,0 +1,10 @@
+info:
+  title: Redis cluster
+  description: Defines a redis cluster, using a single replica
+    replicatedservice for master and replicatedservice for workers.
+
+properties:
+  workers:
+    type: int
+    default: 2
+    description: Number of worker replicas.