Introduce Booths for admin

app/models/conference.rb

@@ -28,6 +28,7 @@ class Conference < ActiveRecord::Base
   has_many :supporters, through: :ticket_purchases, source: :user
   has_many :tickets, dependent: :destroy
   has_many :resources, dependent: :destroy
+  has_many :booths, dependent: :destroy
 
   has_many :lodgings, dependent: :destroy
   has_many :registrations, dependent: :destroy