Reverted [17378] until a public API is available for application labels.

This will allow to solve the i18n of such labels in a more holistic way
without the need to introduce temporary, undocumented mechanisms to
translate them.

Refs #3591, #10436

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17389 bcc190cf-cafb-0310-a4f2-bffc1f526a37