Squashed commit of the following:

commit 6dafd477dd086a082f1d096fae21162f134bf254
Author: Juan Pizarro <jpizarrom@gmail.com>
Date:   Tue Sep 23 16:57:23 2014 -0300

    added is_social_friend

commit b1229cbabf840ccfc184bb0bc2d353dd542a1ca8
Author: Juan Pizarro <jpizarrom@gmail.com>
Date:   Tue Sep 23 16:03:03 2014 -0300

    added SocialFriend
    remove SocialFriendList

commit c21e3244ddf2a3bb67e5431c870fb85bb0e2e56e
Author: Juan Pizarro <jpizarrom@gmail.com>
Date:   Mon Sep 22 17:33:31 2014 -0300

    update to python-social-auth