Tracking & Just Walk logic improvements, geofence changes, networking UX

Tracking & Just Walk logic improvements:
-New BikingStateTrackingDidStop to keep a Just Walk alert from
appearing when getting to destination and stopping tracking
-cleaned up prepareBikeRoute logic and callback functionality
-Added Just Walk alert if the overall walking distance would be longer
to try to pick up a bike, dock it and then walk to the final
destination than it would be to just walk outright
-Added new destinationDetailLabel text for walking to a final
destination after tracking stops

Geofence changes:
-back to a 10m radius

Networking UX:
-Take out detailed AFNetworking error message from alertView in
production release
-Only show alertView when our AFNetworking request fails if app is
active

-More code cleanup