Add rubocop spacing rules

We were following these rules in most places; we just didn't define them
anywhere.

config/environments/production.rb

@@ -56,7 +56,7 @@ Rails.application.configure do
   config.log_level = :warn
 
   # Prepend all log lines with the following tags.
-  config.log_tags = [ :request_id ]
+  config.log_tags = [:request_id]
 
   # Use a different cache store in production.
   config.cache_store = :dalli_store, { value_max_bytes: 2000000 }