[Slider] removed react-draggable dependency (fixes IE!)

[igorbt]

Fixing this bug #708, I ended up that it's better to entirely remove react-draggable dependency. With this change I saw also it seems to be more responsive.
Also, this fixes desynchronization between the mouse position and slider handle.

A (very) little breaking change in the onDragStop and onDragStart APIs - it no longer provides second argument - ui. I think it was useless anyway because it had handle offset in pixels. I cannot think about a scenario when someone really need this. I you don't agree, I can try to add it back by calculating it.

[igorbt]

Fixes #1745 - see #1745 (comment).

[igorbt]

@yongxu, @shaurya947, @KapJI can you please take a look here. I saw you are the last contributors to the Slider component, so maybe you can make a quick review.
The thing is that we use Slider in our product and we had a lot of issues with it (and material-ui issue tracker also if full of slider bugs) and this PR fixed all of them for us.

[KapJI]

I reviewed this PR and tested it locally on the latest Chrome, Safari and Firefox on OS X 10.11. Now handle and cursor don't diverge. Seems good to me. Good job, @igorbt!

[KapJI]

This will call onChange many times with same value during dragging. I think it will be better to call onChange only when value changes.

[igorbt]

Thanks @KapJI for review and for this finding. You are right and I just fixed it, but from setPercent, it seemed more convenient there for me.

[igorbt]

@yongxu, thanks for review!
You are right, percent is not always the same as this.state.percent. This is why in setState passed value is normalized before putting in state:

setPercent(percent, callback) {
    let value = this._alignValue(this._percentToValue(percent));
    let { min, max } = this.props;
    let alignedPercent = (value - min) / (max - min);
    this.setState({value: value, percent: alignedPercent}, callback);
},

[KapJI]

@yongxu comparing percent difference with step is not a good idea, because step is measured in absolute value, not in percent.

[yongxu]

Thanks @KapJI , you were right I didn't think about it. it should be something like(step/(max-min))
@igorbt have solved this in another way, I think it should be good enough!

[igorbt]

@yongxu you are right, just removed that line.

[igorbt]

@shaurya947 can you please also have a look and merge this PR?

[igorbt]

@shaurya947, I just rebased. Can you please also have a look and merge this PR? That's a pain to keep rebasing given the change rate in the library.

[shaurya947]

There you go, thanks @igorbt

[igorbt]

Awsome! Thanks @shaurya947! I think at least 5 bugs shoul be closed now.