Added SparklinesInteractiveLayer
Made it a little interactive

@borisyankov are we going to have this similar interactive layer at some point?
Great PR! Just what I was looking for.
Question. Did you need an updated version of react and react-dom for this?
If not, it's probably making the scope for this PR bigger than it should
It's been 3 years... time sure passes.
Anyways, @qcho had to check my code again. On the issue, I updated react because I was using React.Fragment which is not supported in react 15.
Have updated the PR now and I have removed fragment, reverted the versions back to old one and now am using the svg g tag which works equally well.
Cheers!