Allow empty options to be imported
Allow empty options to be imported

This adds the possibility for importing None type options on non
mandatory option fields.

selahssea/ggrc-core,kr41/ggrc-core,josthkko/ggrc-core,VinnieJohns/ggrc-core,plamut/ggrc-core,andrei-karalionak/ggrc-core,selahssea/ggrc-core,plamut/ggrc-core,j0gurt/ggrc-core,andrei-karalionak/ggrc-core,josthkko/ggrc-core,j0gurt/ggrc-core,edofic/ggrc-core,josthkko/ggrc-core,VinnieJohns/ggrc-core,VinnieJohns/ggrc-core,AleksNeStu/ggrc-core,AleksNeStu/ggrc-core,selahssea/ggrc-core,kr41/ggrc-core,selahssea/ggrc-core,j0gurt/ggrc-core,plamut/ggrc-core,andrei-karalionak/ggrc-core,andrei-karalionak/ggrc-core,edofic/ggrc-core,edofic/ggrc-core,kr41/ggrc-core,j0gurt/ggrc-core,VinnieJohns/ggrc-core,kr41/ggrc-core,plamut/ggrc-core,edofic/ggrc-core,AleksNeStu/ggrc-core,AleksNeStu/ggrc-core,josthkko/ggrc-core