Implement role authorization

app/controllers/admin/schedules_controller.rb

@@ -1,10 +1,14 @@
 module Admin
   class SchedulesController < ApplicationController
-    before_filter :verify_organizer
+    # By authorizing 'conference' resource, we can ensure there will be no unauthorized access to
+    # the schedule of a conference, which should not be accessed in the first place
+    load_and_authorize_resource :conference, find_by: :short_title
+
     skip_before_filter :verify_authenticity_token, only: [:update]
     layout 'schedule'
 
     def show
+      authorize! :update, @conference.events.new
       if @conference.nil?
         redirect_to admin_conference_index_path
         return
@@ -14,6 +18,7 @@ module Admin
     end
 
     def update
+      authorize! :update, @conference.events.new
       event = Event.where(guid: params[:event]).first
       error_message = nil
       if event.nil?