Make rails yarn:install ignore dev dependencies

Author: printercu

railties/lib/rails/tasks/yarn.rake

@@ -1,7 +1,7 @@
 namespace :yarn do
   desc "Install all JavaScript dependencies as specified via Yarn"
   task :install do
-    system("./bin/yarn install --no-progress")
+    system("./bin/yarn install --no-progress --production")
   end
 end