cannot load such file -- bundler/setup (LoadError)
  /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
  /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27/lib/phusion_passenger/loader_shared_helpers.rb:219:in `block in run_load_path_setup_code'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27/lib/phusion_passenger/loader_shared_helpers.rb:333:in `running_bundler'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27/lib/phusion_passenger/loader_shared_helpers.rb:217:in `run_load_path_setup_code'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27//helper-scripts/rack-preloader.rb:96:in `preload_app'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27//helper-scripts/rack-preloader.rb:150:in `<module:App>'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27//helper-scripts/rack-preloader.rb:29:in `<module:PhusionPassenger>'
  /var/lib/gems/1.9.1/gems/passenger-4.0.27//helper-scripts/rack-preloader.rb:28:in `<main>'