Fix for -Wsign-conversion in AFURLConnectionOperation running Xcode 5.1
Resolves a -Wshorten-64-to-32 error on 32bit environments
Merge pull request #1856 from realestate-com-au/bug/xcode51-warnings

Fixes for a couple of errors with Xc5.1
Merge remote-tracking branch 'AFNetworking/AFNetworking/master'