feat(narrative): Add option for expansion listener to ItineraryCarousel

Author: David Emory

lib/components/narrative/itinerary-carousel.js

@@ -16,13 +16,16 @@ class ItineraryCarousel extends Component {
     pending: PropTypes.bool,
     activeItinerary: PropTypes.number,
     hideHeader: PropTypes.bool,
+    onExpand: PropTypes.func,
     setActiveItinerary: PropTypes.func,
     setActiveLeg: PropTypes.func,
     setActiveStep: PropTypes.func
   }
 
   _onItineraryClick = () => {
-    this.setState({expanded: !this.state.expanded})
+    const expanded = !this.state.expanded
+    this.setState({expanded})
+    if (this.props.onExpand) this.props.onExpand(expanded)
   }
 
   _onLeftClick = () => {