Add map click event to MapView

Pass event object to application event aggregator. Register handler
on view 'onShow' and deregister on 'onClose'.
Add mapCenter event handler to MapView

Register handler with app aggregator on view 'onShow' and remove on
'onClose'.
Update FlightLocationEditor on map click events

Event populates location input box with clicked latitude and longitude.
Add 'Map:Click' event handler on view 'onShow', remove on 'onClose'.
Add geocoding to FlightLocationEditor

Add search button to FlightLocationEditor template. Add keypress listener
to js to support submit on enter. Add click listener to search for geocode.
Recenter map on geocode success.