Support tooltip on React Fragments

[AlonBe]

The following code doesn't popup the tooltip: `<Tooltip overlay={this.getOverlay} placement={'bottomLeft'}>

<React.Fragment>
     { anyInnerChild }
</React.Fragment>

`

But when working with "native" components which are not React Fragments - it works

[burtek]

As per docs,

Tooltip requires child node accepts onMouseEnter, onMouseLeave, onFocus, onClick event.

That's why React.Fragment does not work