add relationships for booths

db/migrate/20170530112510_create_booth_requests.rb

@@ -0,0 +1,11 @@
+class CreateBoothRequests < ActiveRecord::Migration
+  def change
+    create_table :booth_requests do |t|
+      t.references :booth, index: true, foreign_key: true
+      t.references :user, index: true, foreign_key: true
+      t.string :role
+
+      t.timestamps null: false
+    end
+  end
+end