Update for newer MM

lib/acts_as_versioned.rb

@@ -1,36 +1,38 @@
+require 'active_support/concern' unless defined?(ActiveSupport)
+
 module MongoMapper
   module Acts
     module Versioned
+      extend ActiveSupport::Concern
+
       VERSION   = '0.0.11'
-      CALLBACKS = [:save_version, :save_version?, :clear_old_versions]
+      CALLBACKS = [:save_version, :clear_old_versions]
 
-      def self.configure(model)
-        model.class_eval do
-          cattr_accessor :versioned_class_name, :non_versioned_keys, :max_version_limit
+      included do
+        cattr_accessor :versioned_class_name, :non_versioned_keys, :max_version_limit
 
-          self.versioned_class_name = :Version
-          self.max_version_limit = 0
-          self.non_versioned_keys = %w(
-            _id _type created_at updated_at creator_id updater_id version
-          )
+        self.versioned_class_name = :Version
+        self.max_version_limit = 0
+        self.non_versioned_keys = %w(
+          _id _type created_at updated_at creator_id updater_id version
+        )
 
-          const_set(versioned_class_name, Class.new).class_eval do
-            include MongoMapper::EmbeddedDocument
+        const_set(versioned_class_name, Class.new).class_eval do
+          include MongoMapper::EmbeddedDocument
 
-            key :version,  Integer
-            key :modified, Hash
-          end
+          key :version,  Integer
+          key :modified, Hash
+        end
 
-          many :versions, :class => "#{self}::#{versioned_class_name}".constantize do
-            def [](version)
-              detect { |doc| doc.version.to_s == version.to_s }
-            end
+        many :versions, :class => "#{self}::#{versioned_class_name}".constantize do
+          def [](version)
+            detect { |doc| doc.version.to_s == version.to_s }
           end
         end
 
-        model.key :version, Integer
-        model.before_save :save_version
-        model.before_save :clear_old_versions
+        key :version, Integer
+        before_save :save_version
+        before_save :clear_old_versions
       end
 
       module InstanceMethods