Request: Please add fast-scroller and header&footer

[AndroidDeveloperLB]

I had to make the fast-scroller myself, but it's probably not the best way to do it: https://github.com/AndroidDeveloperLB/LollipopContactsRecyclerViewFastScroller

It could be nice to have it customizable/extensible like the LayoutManager. Or at least support the already existing classes that extend it?

Also, currently, adding a header/footer is done by adding item/s as real rows with a different type, which is quite annoying to use.