Fixed a few translation related tests:

  * Extended the admin i18n view to also take the admin translation catalogues into account.
  * Use a translation string from the core translations to test LOCALE_PATHS.
  * Fixed Russian translation of singular forms.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15273 bcc190cf-cafb-0310-a4f2-bffc1f526a37