add save_vulnerability_set_nrml to utils.py
add save_vulnerability_set_nrml to utils.py

dynaryu/rmtk,mabevillar/rmtk,GEMScienceTools/rmtk,mabevillar/rmtk,ccasotto/rmtk,dynaryu/rmtk,ccasotto/rmtk,GEMScienceTools/rmtk