Fix undefined fallback variables in build gradle
Fix undefined fallback variables in build gradle

The fallback variables defined in the build gradle are all undefined
DEFAULT_SUPPORT_LIB_VERSION
DEFAULT_GOOGLE_PLAY_SERVICES_VERSION
DEFAULT_FIREBASE_MESSAGING_VERSION
zo0r/react-native-push-notification,zo0r/react-native-push-notification,zo0r/react-native-push-notification