Set config.cache_store in environments file. (#3219)

* Set config.cache_store in application.rb

* Set config.cache_store in environments.

* fix code format.

config/environments/production.rb

@@ -50,6 +50,9 @@ Rails.application.configure do
   # Use a different logger for distributed setups.
   # config.logger = ActiveSupport::TaggedLogging.new(SyslogLogger.new)
 
+  # Use a different cache store in production.
+  config.cache_store = :redis_store, ENV['REDIS_URL'], REDIS_CACHE_PARAMS
+
   # Enable serving of images, stylesheets, and JavaScripts from an asset server.
   # config.action_controller.asset_host = 'http://assets.example.com'