Allow optionsFromProps to be passed at init

[sbellity]

The button classes options are not properly set via setOptions otherwise.

[skratchdot]

I'm going to pull this in. Were you changing the button class via a prop, and it wasn't updating, or was the "initial" value never working? Something like:

<DateRangePicker cancelClass={this.state.myClass} />

The reason I ask, is because I think the change you made is really working b/c you removed the weird "needToInit" hack I added.

I think the real fix is to stop calling this.setOptionsFromProps() in the render() function, and calling it intelligently via some of the other react lifecycle points like componentWillReceiveProps().

I'll look into this when I get a chance. I'll probably update some libs, and look into making better use of the react lifecycle. Then I'll test, update the package version, and publish...