Move events index datatable row to a partial

- clean up columns
- tag unregistered submitters & speakers
- implement caching

app/models/user.rb

@@ -22,6 +22,8 @@ class User < ApplicationRecord
 
   before_create :setup_role
 
+  after_save :touch_events
+
   # add scope
   scope :comment_notifiable, ->(conference) {joins(:roles).where('roles.name IN (?)', [:organizer, :cfp]).where('roles.resource_type = ? AND roles.resource_id = ?', 'Conference', conference.id)}
 
@@ -231,6 +233,10 @@ class User < ApplicationRecord
     end
   end
 
+  def touch_events
+    event_users.each(&:touch)
+  end
+
   ##
   # Check if biography has an allowed number of words. Used as validation.
   #