Add initial support for JSON on map_index view.

Add initial support for JSON on map_index view.

This commit adds initial JSON support to the map_index view.
I am giving each model class a to_dict function that returns
a select number of its instance variables back in the form of
a dictionary, which can then be returned directly by a JSON
renderer. I'm not sure if this is the right way to go, but
it works for now.

I've also ripped out the main "data-calling" piece of each
view callable into a separate function so that the JSON-
enabled view callable can use it. The non-JSON one just
returns the result of that function, while the JSON one
massages the data to be able to make it fit better for
API-like consumption.