Kill trailing whitespace in ruby files

app/controllers/moderator/invitations_controller.rb

@@ -1,15 +1,15 @@
 module Moderator
   class InvitationsController < ApplicationController
     before_filter :moderator_only
-    
+
     def new
     end
-    
+
     def create
       User.find(params[:invitation][:user_id]).invite!(params[:invitation][:level])
       redirect_to moderator_invitations_path
     end
-    
+
     def index
       @users = User.where("inviter_id = ?", CurrentUser.id).paginate(params[:page])
     end