`Grid` supports a new `renderCellRanges` property for customizing the rendering of a window of cells.
This function should implement the following signature:
```js
function renderCellRanges ({
  columnMetadata:Array<Object>,
  columnStartIndex: number,
  columnStopIndex: number,
  renderCell: Function,
  rowMetadata:Array<Object>,
  rowStartIndex: number,
  rowStopIndex: number
}): Array<PropTypes.node>
```
