Some fixes and new bindings.
Updated ignore.
Pass the NSError object to the listener to help with fault diagnosis.
Pass the NSError object to the listener to help with fault diagnosis. Provide a meaningful error when the 'failed' callbacks are invoked for an unauthenticated player.
Makes the domain constant public to allow clients to verify it against the NSError domain.
Updated ignore.
Adds callbacks for when leaderboards view and achievements view are dismissed.
Updated sample to include callbacks for when leaderboards view and achievements view are dismissed.
Merge pull request #76 from outofcoffee/feature/dismiss-callback

Adds callbacks for when leaderboards view and achievements view are dismissed in Game Center.
Merge pull request #75 from outofcoffee/feature/improved-errors

Pass the NSError object to the listener to help with fault diagnosis on Game Center failures.