Ship with OpenLayers world layers

Currently use of MapBox with OpenLayers requires manual configuration of layers (or use of another module that provides layers).

Some layers (e.g. Afghanistan) are not widely useful, but shipping with the global ones might be useful, particularly for features modules wanting to provide presets, so that there can be consistency e.g. between a geotaxonomy preset and one that maps users.

Thoughts? If global layers don't fit here, do they maybe go in a separate download?