FIX: Split by space to support multiple categories export

lib/tasks/export.rake

@@ -1,6 +1,7 @@
 desc 'Export all the categories'
 task 'export:categories', [:category_ids] => [:environment] do |_, args|
   require "import_export/import_export"
+  ids = args[:category_ids].split(" ")
 
   ImportExport.export_categories(args[:category_ids])
   puts "", "Done", ""