Add option for parentheses around JSX.

I think prettier should have an option ~for TypeScript~ to omit JSX parentheses.

Instead of this:
```tsx
public render(): JSX.Element {
    return (
        <div>
            <div>Hello world!</div>
        </div>
    );
}
```

Expected behavior:
```tsx 
public render(): JSX.Element {
    return <div>
        <div>Hello world!</div>
    </div>;
}
```

