Add the listing model. Rename @json -> @hash for consistency

lib/paapi.rb

@@ -2,6 +2,7 @@ require 'paapi/version'
 
 require 'paapi/client'
 require 'paapi/item'
+require 'paapi/listing'
 require 'paapi/response'
 
 module Paapi

lib/paapi/response.rb

@@ -17,10 +17,7 @@ module Paapi
     end
 
     def result_count
-      @json.dig('SearchResult', 'TotalResultCount')
-    end
-
-
-
+      @hash.dig('SearchResult', 'TotalResultCount')
+    end
   end
 end