Fix bike Mongo bug; add GoogleDir optimized route.

Add:
	py/google_directions.py
		-add module for interaction with the Google Directions API;
		currently contains a single function, get_waypoint_order, which
		returns an ordered list of waypoints optimized by distance.

Fix:
	py/utils.py
		-add a statement to remove all pre-existing citi-bike depot
		documents from the citi_bike collection in our Mongo database,
		which wouldn't have been replaced by the insertion of new data
		with identical keys (different hash IDs).