Clean up redis configuration. Allow using REDIS_URL to set advanced (#2732)

connection options instead of setting REDIS_HOST etc individually

Close #1986

config/environments/development.rb

@@ -16,14 +16,6 @@ Rails.application.configure do
   if Rails.root.join('tmp/caching-dev.txt').exist?
     config.action_controller.perform_caching = true
 
-    config.cache_store = :redis_store, {
-      host: ENV['REDIS_HOST'] || 'localhost',
-      port: ENV['REDIS_PORT'] || 6379,
-      db: 0,
-      namespace: 'cache',
-      expires_in: 1.minute,
-    }
-
     config.public_file_server.headers = {
       'Cache-Control' => 'public, max-age=172800',
     }