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

app/views/admin/events/_proposal.html.haml

@@ -97,7 +97,7 @@
                                               on_text: 'Yes',
                                               off_text: 'No' }
           - if @event.require_registration
-            = registered_text(@event)
+            Registered: #{registered_text(@event)}
 
       -if @program.languages.present?
         %tr
@@ -105,7 +105,6 @@
             %b Language
           %td
             = @event.language
-
       - if !@event.room.nil?
         %tr
           %td