CODEBASE-251: Using add/remove folder creates extraneous flash messag…

…e on next page loaded.

Discarding flash messages on xhr (see http://www.whatcodecraves.com/articles/2008/12/13/rails_flash_with_ajax/ )

app/controllers/application_controller.rb

@@ -7,6 +7,7 @@ class ApplicationController < ActionController::Base
   before_filter :default_html_head # add JS/stylesheet stuff
   filter_parameter_logging :password, :password_confirmation
   helper_method :current_user_session, :current_user
+  after_filter :discard_flash_if_xhr
 
   def user_class; User; end
 
@@ -96,6 +97,10 @@ def current_user
       return @current_user if defined?(@current_user)
       @current_user = current_user_session && current_user_session.user
     end
+
+    def discard_flash_if_xhr
+      flash.discard if request.xhr?
+    end
 
 end