Bump afnetworking to the 1.3.2 release

Version is https://github.com/AFNetworking/AFNetworking/releases/tag/1.3.2

This silences some console logging noise on 10.9.

```
16/08/2013 8:30:37.610 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:37.828 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:37.885 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:38.021 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:38.554 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:38.850 pm GitHub[5380]: NSScanner: nil string argument
16/08/2013 8:30:38.942 pm GitHub[5380]: NSScanner: nil string argument
```