Remove unneeded /nix/rw-store creation when using readOnlyStore
activation: Don't use double quotes in boot loader warning message, it messes up perl system call
switch-to-configuration.pl: Fix parsing of comments in fstab, hash-tokens inside strings are not comments.
nixos-install: Handle /nix/var/nix/db being on a separate filesystem

This is the case on S3-backed EC2 instances.
Auto-create a keypair during EBS AMI creation
Doh
nslcd: Adjust service definition to systemd
mpd: Adjust service definition to systemd
Parameterise the path to nixpkgs.

This makes it possible to build several NixOS systems that use different
nixpkgs in the same nix-build invocation. Today, you can't do that since
the <nixpkgs> path reference is hard-coded in lib/eval-config.nix.