Merge branch 'hotfix/add_placeholder_to_slug'

* hotfix/add_placeholder_to_slug:
  add placeholder
Merge branch 'release/0.2.4'

* release/0.2.4:
  fix web/admin/numbers index view
  add admin/numbers_controller
  fix comments controller
  fix comments form
  add admin_comment
  add solution state to comment
fix decorator
Merge branch 'hotfix/fix_decoratir' into develop

* hotfix/fix_decoratir:
  fix decorator