Box styling on TimeMarker doesn't work

# 🐛Bug report

Styling the box using `infoStyles = {..., box: ...}` does not do anything on a `TimeMarker` component.

I believe that this is because:

line 73 of TimeMarker.js unpacks the box property
`style: this.props.infoStyle.box,`

then renders a label component which attempts to again unpack the box property style.box

```
function mergeStyles(style, isCentered) {
return {
boxStyle: merge(true, defaultBoxStyle, style.box ? style.box : {}),
labelStyle: merge(
true,
isCentered ? defaultTextStyleCentered : defaultTextStyle,
style.label ? style.label : {}
)
};
}
```

(to anyone needing a workaround, use: `infoStyles = {..., box: { box: {...} }}`)