Added checks for running on device around android debug logging.
Changed iOS OnPurchaseSucceeded to use json in the same way as android, so that it can contain receipt data.
Replacing usage of deprecated [SKProduct paymentWithProductIdentifier] https://developer.apple.com/LIBRARY/ios/documentation/StoreKit/Reference/SKPaymentRequest_Class/index.html#//apple_ref/occ/clm/SKPayment/paymentWithProductIdentifier:
Storing SKProduct in the skuMap as its required for making purchases later in the iOS process.
Adding support for iOS receipts.