Add ViewObservables.listViewScroll(AbsListView).

I personally find this test difficult to digest. The first 20 or so lines are setup code, and it seems to use nested `inOrder` clauses, I've never seen that before. Did you mean to write:

`InOrder inOrder = inOrder(observerA, observerB)`

?

In general, could you try to break this test down a bit? Tests shouldn't stretch over more than a few lines of code if possible.