update MRI servers and do not auto-require them + put the in a logical (server) group

rack/Gemfile-ruby

@@ -3,5 +3,7 @@ source 'http://rubygems.org'
 gem 'rack', '1.5.2'
 gem 'json', '1.7.6'
 
-gem 'passenger', '4.0.19'
-gem 'unicorn', '4.6.2'
+group :server do
+  gem 'passenger', '4.0.44', :require => false
+  gem 'unicorn', '4.8.3', :require => false
+end