title: Dispose in RecyclerView items
body: <p>I have a RecyclerView with Custom views in it.
  I make some calls with RX in these views and I want to dispose (to avoid memory leaks) when the view is not necessary anymore.
  The problem is the RecyclerView recycles the views and the "dispose" call is in the "onDetachedFromWindow" method, so sometimes when I scroll back up I can see views that didn't finish their RX call and got disposed.
  What Can I do to avoid such situations and what is the best practice to use RX and disposables?</p>