dev-todo-mvvm-rxjava: Tasks list is not restoring scroll position on config changes

I guess this issue goes to @florina-muntenescu (who is the project owner).

I'm aware this branch is still under development, but I noticed this example is not handling restoring the scroll position properly on `TasksFragment`, instead, the scroll position gets reset to the top on orientation changes. I tested this by adding a lot of tasks to the list and then rotating my device.

I presume this is because the `TasksFragment.updateView()` method gets called after the layout pass of the activity and thus the `RecyclerView` does not know its correct size at rendering time.

It would be awesome if we are provided with a working example on how to restore the scroll position properly using MVVM and RxJava together.

Here is the link to [TasksFragment.](https://github.com/googlesamples/android-architecture/blob/dev-todo-mvvm-rxjava/todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragment.java)

Thank you for your help.

Start with todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragment.java, especially updateView(), and reproduce the issue by creating many tasks and rotating the device. Done means the Tasks list keeps its scroll position across configuration changes in the dev-todo-mvvm-rxjava example.

Written by the indexing model from the issue text.