Truck locations

This PR includes:

-Custom map annotations for trucks
-Clustering of trucks in close proximity
-Using the TruckManager that Josh wrote to request data

It's commonly best practice to put super.init() at the end of init methods because parent classes can end up calling child classes instance methods. If its first, as it is here, this could result in an app crash because instance methods may try to access variables that are uninitialized. The compiler should catch this, however, I think the way countLabel was declared silences this warning.