fix revision count and drop observers

app/models/room.rb

@@ -1,4 +1,5 @@
 class Room < ActiveRecord::Base
+  include RevisionCount
   belongs_to :venue
   has_many :event_schedules, dependent: :destroy
 
@@ -10,6 +11,10 @@ class Room < ActiveRecord::Base
 
   validates :size, numericality: { only_integer: true, greater_than: 0 }, allow_nil: true
 
+  def conference
+    venue.conference
+  end
+
   private
 
   def generate_guid