BarChart: missing function argument at styling

[siavelis]

Documentation says that the component provides a prop for styling using a function. Like this below:

function: `(event, column) => {}` The function should return a style object.

But the event is not passed in the function (see

react-timeseries-charts/src/components/BarChart.js

Lines 163 to 164 in 4312901

	} else if (_.isFunction(this.props.style)) {
	style = this.props.style(column);

)

It is an easy fix, so I'm submitting a PR.