Fixed #8638 -- Added documentation on how to redirect email to a dummy server...

Fixed #8638 -- Added documentation on how to redirect email to a dummy server for testing purposes. Thanks to Rob Hudson and Marc Fargas for their work on the draft for this change.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9793 bcc190cf-cafb-0310-a4f2-bffc1f526a37