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		which wouldn't have been replaced by the insertion of new data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).
Add styling for background image and title.

Add:
	static/css/style.css
		-add CSS for full-page background image, and white-color title.
Merge branch 'mapsdev'