FIX: faster update of all badges

Introduced badge triggers, introduced concept of badge that happens due to a post but has the post hidden

Delta badge grant happens once a minute, backed by redis

app/models/user_stat.rb

@@ -1,6 +1,7 @@
 class UserStat < ActiveRecord::Base
 
   belongs_to :user
+  after_save :trigger_badges
 
   # Updates the denormalized view counts for all users
   def self.update_view_counts
@@ -64,6 +65,12 @@ class UserStat < ActiveRecord::Base
     cache_last_seen(Time.now.to_f)
   end
 
+  protected
+
+  def trigger_badges
+    BadgeGranter.queue_badge_grant(Badge::Trigger::UserChange, user: self.user)
+  end
+
   private
 
   def last_seen_key