Dont Mutate Color Object
Hi,

I had unexpected side effects because the color I was passing as a prop to the color picker was being modified directly. More precisely, I was passing a HSL color and the `s` and `l` properties were converted to string percentages.

```javascript
{
    h: 0,
    s: 1,
    l: 0.5
}
```
was converted to
```javascript
{
    h: 0,
    s: "100%",
    l: "50%"
}
```
which broke other parts of my code.

I made a quick demo of this issue: https://codesandbox.io/s/P1nlQ60o4
If you click the button twice you will see that the state has been modified! My guess is that the state was modified directly on the first click and didn't trigger rendering, which the second click does through the `setState` call.

As a workaround I clone my color before passing it to the color picker, but I should be able to trust a component with my props as per the React documentation: 

> [All React components must act like pure functions with respect to their props.](https://facebook.github.io/react/docs/components-and-props.html#props-are-read-only)