Topology View Maps: Refactor to simplify introduction of new maps.

As a developer, I would like to be able to add a new geographic map as background to the Topology View in a simple, consistent manner.

Notes:
Currently, adding a new region map is messy - either trying to identify map segments from the countries.topojson file and writing a selection predicate for it, or by adding a new custom .topojson file. In both cases, code needs to be added to topo.js (and other topo*.js files?) and MapSelectorMessageHandler.java, and the product recompiled.

It would be very nice if an application could "register" a new map when the application is activated (and removed when deactivated) in such a way as to have it included in the selection box ('G' keyboard shortcut).

Additionally, there is cleanup required in the countries.topojson file as there are many fields that are never referenced – it's just deadweight that really shouldn't be downloaded to the browser.