add helper file

app/helpers/notifier_helper.rb

@@ -0,0 +1,11 @@
+module NotifierHelper
+  def post_message(post, opts={})
+    if post.respond_to? :formatted_message
+      message = truncate(post.formatted_message(:plain_text => true), :length => 200)
+      message = process_newlines(message) if opts[:process_newlines]
+      message
+    else
+      I18n.translate 'notificer.a_post'
+    end
+  end
+end