Fix deprecation warnings

Author: dariusf

config/environments/production.rb

@@ -22,7 +22,7 @@
 
   # Disable serving static files from the `/public` folder by default since
   # Apache or NGINX already handles this.
-  config.serve_static_files = ENV['RAILS_SERVE_STATIC_FILES'].present?
+  config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
   # Compress JavaScripts and CSS.
   config.assets.js_compressor = :uglifier

config/environments/test.rb

@@ -13,7 +13,7 @@
   config.eager_load = false
 
   # Configure static file server for tests with Cache-Control for performance.
-  config.serve_static_files   = true
+  config.public_file_server.enabled = true
   config.static_cache_control = 'public, max-age=3600'
 
   # Show full error reports and disable caching.