fix(ios): foreground notification property

check if react native's app state is unknown to verify if
app came from background

Author: Sebastian Pernett

index.js

@@ -351,7 +351,8 @@ Notifications._transformNotificationObject = function(data, isFromBackground = n
   if ( isFromBackground === null ) {
     isFromBackground = (
       data.foreground === false ||
-      AppState.currentState === 'background'
+      AppState.currentState === 'background' ||
+      AppState.currentState === 'unknown'
     );
   }