Add email notifications for events registrations, add switch-checkboxes, create EventsRegistrations controller, separate page for events that require registration

app/jobs/deleted_event_registration_automatically_job.rb

@@ -0,0 +1,7 @@
+class DeletedEventRegistrationAutomaticallyJob < ActiveJob::Base
+  queue_as :default
+
+  def perform(conference, user, event)
+    Mailbot.deleted_event_registration_automatically(conference, user, event).deliver_now
+  end
+end