Made Cocoon Rails 3.1 compatible:

- moved cocoon.js to app/assets/javascripts
- adapted install-generator accordingly (for rails 3.0.x)
- made it an engine instead of railtie (to use the asset pipeline)

lib/cocoon.rb

@@ -1,7 +1,7 @@
 require 'cocoon/view_helpers'
 
 module Cocoon
-  class Railtie < ::Rails::Railtie
+  class Engine < ::Rails::Engine
 
     config.before_initialize do
       config.action_view.javascript_expansions[:cocoon] = %w(cocoon)

lib/generators/cocoon/install/install_generator.rb

@@ -2,10 +2,18 @@ module Cocoon
   module Generators
     class InstallGenerator < ::Rails::Generators::Base
       source_root File.expand_path('../templates', __FILE__)
-      desc "This generator installs the javascript needed for cocoon"
 
+      if ::Rails::VERSION::MAJOR == 3 && ::Rails::VERSION::MINOR >= 1
+        # for Rails 3.1 no installing is needed anymore, because of the asset pipeline
+        desc "Installing is only needed for rails 3.0.x"
+        def do_nothing
+          puts "Installing is no longer required since Rails 3.1"
+        end
+      else
+        desc "This generator installs the javascript needed for cocoon"
         def copy_the_javascript
-        copy_file "cocoon.js", "public/javascripts/cocoon.js"
+          copy_file "../../../app/assets/javascripts/cocoon.js", "public/javascripts/cocoon.js"
+        end
       end
 
     end