Add custom configuration for ABI IR channels with colormaps
As discussed with the NOAA Imagery team, people like IR channels with colors!!! Kathy and I aren't really comfortable changing defaults in Geo2Grid (@graemem let me know what you think). Adding the custom configuration just to Geo2Grid in GeoSphere seems easy and non-confrontational. The TODO means adding custom configs to geosphere-geo2grid but also updating the colormaps in the API (including the C07 limit changes implemented upstream in G2G 1.2).