4.0.2 - Drop-in fetches payment methods automatically

• If the Client Token has a Customer ID, Drop-in will automatically fetch the customer's vaulted payment methods.
  • A bug in 4.0.0-4.0.1 prevented Drop-in from fetching payment methods even if a Customer ID is provided in the Client Token; apps needed to call fetchPaymentMethodsOnCompletion before presenting Drop-in.
  • You can still call fetchPaymentMethodsOnCompletion to pre-fetch payment methods, so that Drop-in doesn't need to show its own loading activity indicator.
• Prevent calling requestsDismissalOfViewController on iOS 8 when there is nothing to dismiss. (Merge #199 - thanks, @Reflejo!)
• Drop-in Add Payment Method fixes
  • Show/hide CVV and postal code fields without flicker
• Use Save bar button item in upper right to add additional payment methods
• BTPayPalDriver will not call BTAppSwitchDelegate callback methods when SFSafariViewController is presented (Issue #188)