Update componentWillMount to use setState

[mynameistechno]

First off, thanks for this module. This is exactly what I need. Second, heads up, React now throws a warning if you set state directly in componentWillMount instead of using setState:

index.js:2214 Warning: SpinnerComponent.componentWillMount(): Assigning directly to this.state is deprecated (except inside a component's constructor). Use setState instead.

It also seems like componentWillUpdate will be deprecated altogether in React 17 ...

Cheers!

[Simply007]

I have fixed the issue in #3