Fixed #16185, #15675 -- Added the ability for test runners to define custom options, and to specify a custom test runner at the command line. Thanks to Dmitry Jemerov and Mikołaj Siedlarek for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16352 bcc190cf-cafb-0310-a4f2-bffc1f526a37