Fix FCM compatibility and Android package definition

Author: KieranLafferty

ios/onesignal_flutter.podspec

@@ -13,7 +13,7 @@ Pod::Spec.new do |s|
   s.source_files = 'Classes/**/*'
   s.public_header_files = 'Classes/**/*.h'
   s.dependency 'Flutter'
-  s.dependency 'OneSignal', '2.16.2'
+  s.dependency 'OneSignal',  '2.16.3'
   s.ios.deployment_target = '8.0'
   s.static_framework = true
 end

pubspec.yaml

@@ -6,9 +6,9 @@ homepage: https://github.com/OneSignal/OneSignal-Flutter-SDK
 
 flutter:
   plugin:
-    androidPackage: com.onesignal.flutter
     platforms:
       android:
+        package: com.onesignal.flutter
         pluginClass: OneSignalPlugin
       ios:
         pluginClass: OneSignalPlugin