Squashed commit of the following:

commit 877ef81d21731b54b4b87d9b88ce982e074d3c8b
Merge: 601c026 7bdd4ec
Author: Mattt Thompson <m@mattt.me>
Date:   Wed Jun 11 08:46:54 2014 -0700

    Merge branch 'master' of github.com:neonichu/AFNetworking into neonichu-master

commit 7bdd4ecbae26778f3d2758bade024b4f3922db24
Author: Boris Bügling <boris@icculus.org>
Date:   Tue Jun 10 14:59:27 2014 +0200

    Add nil check before dereference of `error`.