add missing LUA import for clusterstore and fix prestashop docker example

examples/prestashop/docker-compose.yml

@@ -65,7 +65,8 @@ services:
     networks:
       - bw-services
 
-  image: mariadb
+  mydb:
+    image: mariadb
     volumes:
       - db-data:/var/lib/mysql
     networks:

src/common/confs/server-http/access-lua.conf

@@ -1,9 +1,10 @@
 access_by_lua_block {
 
-local logger	= require "logger"
-local datastore	= require "datastore"
-local plugins	= require "plugins"
-local utils		= require "utils"
+local logger		= require "logger"
+local datastore		= require "datastore"
+local plugins		= require "plugins"
+local utils			= require "utils"
+local clusterstore	= require "clusterstore"
 
 -- Don't process internal requests
 if ngx.req.is_internal() then