Single database for multiple shops

Use ActsAsTenant as Multi-tenancy for shops

See below files:
- app/controllers/concern/multi_tenancy.rb
- app/models/application_record.rb
- app/models/shop.rb

An initializer can be created to control option in ActsAsTenant.
config/initializers/acts_as_tenant.rb
require 'acts_as_tenant/sidekiq'
ActsAsTenant.configure do |config|
  config.require_tenant = false # true
end

more details: https://github.com/ErwinM/acts_as_tenant

app/controllers/api/orders_controller.rb

@@ -46,7 +46,7 @@ class Api::OrdersController <  Api::ApiController
       @tax_profile = TaxProfile.where("lower(group_type)='cashier'")
     # end
 
-    @shop = Shop.first
+    @shop = Shop.current_shop
     puts "Hello world"
     puts @shop.to_json
     return @shop.to_json