Organize all subdomains under its model heading

[christinaholtNOAA]

While this tasks is mainly a web-graphics task, the create_graphics.py driver script needs to be updated to understand that a "full" domain could be a subdomain of a larger model if the grib file was created via wgrib2 subsetting. The products of these cutouts should behave similarly to the subdomains already created within the graphics.

This should be a light Python effort to map between "full" and NA, HRRR_grid, and AK_grid, for example.