Going green: allow to use bbox param, along lon, lat, and zoom
Going green: allow to use bbox param, along lon, lat, and zoom

The `bbox` param was removed from the base controller, the rest kept
working as they are declared in the base, but it's better to declare
them here as well.

Fixes #735.

CartoDB/Windshaft-cartodb,CartoDB/Windshaft-cartodb,CartoDB/Windshaft-cartodb,CartoDB/Windshaft-cartodb