環境にあわせてrake db:seedを実行する

http://stackoverflow.com/questions/16808471/ruby-on-rails-way-to-create-different-seeds-file-for-environments

db/seeds/development.rb
db/seeds/test.rb
db/seeds/production.rb

load(Rails.root.join( 'db', 'seeds', "#{Rails.env.downcase}.rb"))

$ rake db:seed RAILS_ENV=production