Don't re-export GeoFormatTypes

[evetion]

And maybe we shouldn't export in GeoFormatTypes itself?

julia> using Rasters

julia> GeoJSON
GeoJSON

julia> using GeoJSON
WARNING: using GeoJSON.GeoJSON in module Main conflicts with an existing identifier.
ERROR: importing GeoJSON into Main conflicts with an existing global

julia> @which GeoJSON
GeoFormatTypes