#217 Fixed radio selects.

The radio selects weren't changing their respective state variables upon being clicked. I'm not entirely sure if valueLink works for radio selects so I put the onChange handler in, but there may be a more concise way of adjusting the state variable upon a change.
First, let's rename `school_location` to `school_international`, because the name is very misleading.

Second, as mentioned in my previous comment, and in the React docs[1], a radio button is controlled by the `checked` prop. This component should have `value={false}` because it's not international, and thus should have `checked={!this.state.school_international}`.

The other one radio button, representing the international option, should have `value={true}` and `checked={this.state.school_international}`.

[1] http://facebook.github.io/react/docs/forms.html#interactive-props