Remove unused .gitmodules file.
Remove unused .gitmodules file.

stuart-thackray/nitrogen,joaohf/nitrogen,stuart-thackray/nitrogen,kevinmontuori/nitrogen,nitrogen/nitrogen,kevinmontuori/nitrogen,choptastic/nitrogen,joaohf/nitrogen,nitrogen/nitrogen,stuart-thackray/nitrogen,kevinmontuori/nitrogen,choptastic/nitrogen,joaohf/nitrogen,choptastic/nitrogen,nitrogen/nitrogen