mapView changes in startBiking:

-Refresh station data, calculate distances to destination and closest
station to user with >= 1 bike, adjust map zoom/pan to fit start and
finish POIs, only display pertinent annotations
-Made userCoordinate a public property in LocationDataController.h
-Added location sort feature for distance from destination
-Upped max stations to parse to 2000 (need to optimize)
-Added eventual "Bike Here" button to storyboard