Release 1.0.0

Switch to semantic versioning
Update iOS SDK to 2.1.0
Update Android SDK to 5.3.0

Remove old Apple Search Ads methods, these APIs are being shutdown by Apple.
Remove deprecated userCompletedAction methods
Remove deprecated credit related methods. Backend has been shutdown.

Add support for deferred initialization. This will force the underlying Android/iOS code to wait for the C# code to register a callback.
- Create /Assets/StreamedAssets/branch.json
- Add deferInitForPluginRuntime set to true

Add support for logging via branch.json

Sample branch.json

{
  "enableLogging": true,
  "deferInitForPluginRuntime": true
}