Fixed rare crash when verifying transactions on iOS 5.1.1.

Maybe this crash is caused by Jailbreak or by malicious users who try to crack IAP. I have not been able to repro it myself, but I have seen reports of it on my deployed App.
Merge pull request #29 from rsanchezsaez/dev

Fixed rare crash when verifying transactions on iOS 5.1.1.
Refactoring pull request
Update AFNetworking to 1.3.1.
Support SSL certificate pinning.
Merge pull request #35 from dlackty/AFNetworking-1.3.1

Support AFNetworking 1.3 SSL Pining
[Issue #30] Adding typedef for CargoBayStatusCode
Bumping version to 0.3.3