Feature Request: prop for pop-up card

[awatson1978]

Current designs call for a pop-up or overlay card, that can inspect contents of a data point on hGraph.

It would be ideal to be able to feed in an external React component via a prop. Possible API might look like the following:

          <HGraph
            data={ data.currentData }
            width={ graphSize }
            height={ graphSize }
            healthyRangeFillColor={themePrimaryColor}
            showScore={ false }
            margin={{ top: 140, right: 72, bottom: 140, left: 72 }}      
            popUpPosition={['bottom', 'right']} // auto?
            popUpComponent={<SimplePopUp theme="dark" />}
          />