fix import tallty_excel

lib/tallty_import_export/import.rb

@@ -43,6 +43,10 @@ module TalltyImportExport
       end
     end
 
+    def tallty_excel
+      TalltyImportExport::Excel
+    end
+
     def process_options options
       options = options.with_indifferent_access
       self.headers = options.delete(:headers) || []