map docker container ports to allow access easier to memcache

this eases memcached interaction from your host, e.g.,
$ echo "get :1:LICENSE" | nc localhost 11211

tools/docker-compose.yml

@@ -32,6 +32,8 @@ services:
     image: postgres:9.4.1
   memcached:
     image: memcached:alpine
+    ports:
+      - "11211:11211"
   rabbitmq:
     image: rabbitmq:3-management
     ports: