Import Textblock for React

Hello!
First of all, this framework seems pretty cool. Thank you for that!

But I have some problem using it in a React app.

**Expected behaviour in App.js:**

```
import React, { Component } from "react";
import "./App.scss";
import Textblock from "textblock";

class App extends Component {
componentDidMount() {
Textblock([
{
target: "h3",
minWidth: 400,
maxWidth: 800,
minWidthFontSize: 18,
maxWidthFontSize: 24,
minWidthLineHeight: 1.33,
maxWidthLineHeight: 1.2,
units: "px"
}
]);
}

render() {
return

);
}
}

export default App;
```

I guess this is the ES6 way to do it. This is mentioned here: https://github.com/glyphic-co/textblock/issues/7#issuecomment-364515428
**Current behavior**
As it seems now, I have to do this in e.g. index.html the old fashioned way.