Only use DelayedJob in production

In development just let the default async adaptor be used so
that people don't need to run a daemon.

config/environments/production.rb

@@ -99,4 +99,7 @@ Rails.application.configure do
 
   # Enable autoloading of dependencies.
   config.enable_dependency_loading = true
+
+  # Use delayed job to queue jobs in production.
+  config.active_job.queue_adapter = :delayed_job
 end