Change ckeditor gem and kaminari in gemfile

app/models/ckeditor/asset.rb

@@ -0,0 +1,7 @@
+class Ckeditor::Asset
+  include Ckeditor::Orm::Mongoid::AssetBase
+
+  delegate :url, :current_path, :size, :content_type, :filename, :to => :data
+  
+  validates_presence_of :data
+end

app/models/ckeditor/attachment_file.rb

@@ -0,0 +1,7 @@
+class Ckeditor::AttachmentFile < Ckeditor::Asset
+  mount_uploader :data, CkeditorAttachmentFileUploader, :mount_on => :data_file_name
+
+  def url_thumb
+    @url_thumb ||= Ckeditor::Utils.filethumb(filename)
+  end
+end

app/models/ckeditor/picture.rb

@@ -0,0 +1,7 @@
+class Ckeditor::Picture < Ckeditor::Asset
+  mount_uploader :data, CkeditorPictureUploader, :mount_on => :data_file_name
+
+  def url_content
+    url(:content)
+  end
+end