Make the VMs accept the derivations morph sends

morph/grid/local/Vagrantfile

@@ -33,6 +33,7 @@ Vagrant.configure("2") do |config|
   end
 
   # To make the VMs assign the static IPs to the network interfaces we need a rebuild:
+  config.vm.provision "shell", inline: "echo '{nix.trustedUsers = [ \"@wheel\" \"root\" \"vagrant\" ];}' > /etc/nixos/custom-configuration.nix"
   config.vm.provision "shell", inline: "nixos-rebuild switch"
 
   config.trigger.after :up do |trigger|