Add log levels, variadic method signatures
Use new sharedLogger info level in analytics post logging
Add BTPaymentProviderTypeApplePay, sketch support down to POST
Add Apple Pay specs
Access first returned Apple Pay payment method safely
Only dismiss PKPaymentAuthorizationViewController when it finishes
Add specs for BTPaymentProvider's PKPaymentAuthorizationViewControllerDelegate implementation
Add BTApplePayPaymentMethod to BTClient
Add simple BTClient saveApplePayPayment:success:failure integration spec
Get Apple Pay configuration from BTClient

Add Apple Pay option to One Touch demo
Move Apple Pay Configuration to Braintree/API
Add Apple Pay status 'mock' vs 'production'. In mock send empty token.
Account for Apple Pay status when determining whether is available
Create UI for Apple Pay mock mode
Add stateful support for Apple Pay cancelation in BTPaymentProvider
Create BTPaymentApplePayProvider
Implement authorizeApplePay in BTPaymentApplePayProvider
Move Apple Pay authorization logic out of BTPaymentProvider, into dedicated class
Change appearance of Custom Apple Pay Button to use official Apple Pay assets
Add documentation to Apple Pay related headers