Added code to get GamerInfo

With these small changes you can easily get the username, to be used in high-score lists or wherever.
IAP is not maybe the right place for it, but I found it easy to access thanks to the wrapper you already provided and thought I would share my solution.

The GamerInfo is saved in the cloud, so it will fail if there is no internet connection, but it will also instantly update if you change your username in the ouya dev portal, so it's easy to test.