More redux work. User creation/retrieve

lib/redux/userReducer.dart

@@ -0,0 +1,9 @@
+import 'actions.dart';
+import '../models/user.dart';
+
+User userReducer(User user, action) {
+  if (action is OnUserCreatedAction) return user.copyWith(userId: action.userId);
+  if (action is OnUserTokenAction) return user.copyWith(token: action.token);
+  if (action is OnUserLangAction) return user.copyWith(lang: action.lang);
+  return user;
+}