Clean old rails2 style code

config/initializers/4_resque.rb

 # Custom Redis configuration
-rails_root  = ENV['RAILS_ROOT'] || File.dirname(__FILE__) + '/../..'
-rails_env   = ENV['RAILS_ENV'] || 'development'
-config_file = File.join(rails_root, 'config', 'resque.yml')
+config_file = Rails.root.join('config', 'resque.yml')
 
 if File.exists?(config_file)
   resque_config = YAML.load_file(config_file)
-  Resque.redis = resque_config[rails_env]
+  Resque.redis = resque_config[Rails.env]
 end
 
 # Queues