Only import the 'iscsi' singleton when really needed
Only import the 'iscsi' singleton when really needed

If its imported for the class the import happens when the class is being
initialized and thus when the module is imported. Initializing the iscsi
singleton may take time (especially when things go wrong) which makes the import
take more time than an import should take (basically none).

jkonecny12/blivet,vojtechtrefny/blivet,vpodzime/blivet,AdamWill/blivet,AdamWill/blivet,rhinstaller/blivet,rvykydal/blivet,jkonecny12/blivet,vojtechtrefny/blivet,rhinstaller/blivet,rvykydal/blivet,vpodzime/blivet