Fixed #2879 -- Added support for the integration with Selenium and other...

Fixed #2879 -- Added support for the integration with Selenium and other in-browser testing frameworks. Also added the first Selenium tests for `contrib.admin`. Many thanks to everyone for their contributions and feedback: Mikeal Rogers, Dirk Datzert, mir, Simon G., Almad, Russell Keith-Magee, Denis Golomazov, devin, robertrv, andrewbadr, Idan Gazit, voidspace, Tom Christie, hjwp2, Adam Nelson, Jannis Leidel, Anssi Kääriäinen, Preston Holmes, Bruno Renié and Jacob Kaplan-Moss.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17241 bcc190cf-cafb-0310-a4f2-bffc1f526a37