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

app/jobs/updated_max_attendees_automatically_job.rb

@@ -0,0 +1,13 @@
+class UpdatedMaxAttendeesAutomaticallyJob < ActiveJob::Base
+  queue_as :default
+
+  def perform(event, users_emails=nil)
+    if users_emails.present?
+      event.program.conference.email_settings.updated_max_attendees_automatically_body << "\n\nThe following users have been unregistered from your event:\n #{users_emails}"
+    end
+
+    event.users.uniq.each do |user|
+      Mailbot.updated_max_attendees_automatically(event.program.conference, user, event).deliver_now
+    end
+  end
+end