V2 (atomiks#46)

* React 16.8 peer dep

* ref forwarding fixes atomiks#35

* Nesting/multiple test + demo

* Update README.md

* Add typings for V2 (atomiks#47)

* Fix component types

* ignoreAttributes by default

* Add propTypes to TippyGroup

* Add missing TippyGroup types (atomiks#48)

* Fix TippyGroup types

* Add notes on multiple tippys

* tippy.js 4

1.1.1

Add notes for the isVisible prop

remove beta reference

remove babelHelpers

add package fields