Add nix.conf options for -k and -K
Add nix.conf options for -k and -K

Fixes #1084

shlevy/nix,shlevy/nix,shlevy/nix,pikajude/nix,peti/nix,shlevy/nix,vcunat/nix,layus/nix,peti/nix,dtzWill/nix,dezgeg/nix,pikajude/nix,rycee/nix,layus/nix,ehmry/nix,vcunat/nix,NixOS/nix,NixOS/nix,ehmry/nix,vcunat/nix,zimbatm/nix,dezgeg/nix,rycee/nix,NixOS/nix,bennofs/nix,peti/nix,zimbatm/nix,peti/nix,peti/nix,ehmry/nix,dtzWill/nix,dtzWill/nix,vcunat/nix,NixOS/nix,ehmry/nix,bennofs/nix,dezgeg/nix,dtzWill/nix,dezgeg/nix,rycee/nix,dezgeg/nix,layus/nix,NixOS/nix,dtzWill/nix,layus/nix,pikajude/nix,zimbatm/nix,bennofs/nix,rycee/nix,layus/nix,zimbatm/nix,ehmry/nix,ehmry/nix,rycee/nix,bennofs/nix,shlevy/nix