fix(rangeSlider): handles now support stacking (#1129)
fix(rangeSlider): handles now support stacking (#1129)

It was already supported in noUiSlider, just we missed the right css
class.

Since noUiSlider is not really BEM, we cannot use the element
modifier() notation.
algolia/react-instantsearch,algolia/instantsearch.js,algolia/instantsearch.js,algolia/react-instantsearch,algolia/instantsearch.js,algolia/react-instantsearch,algolia/react-instantsearch