i3: Allow to pass a configuration file.

With this it's now possible to directly embed a configuration file
using `services.xserver.windowManager.i3.configFile = path`, which then
will be used instead of the one in the users home directory.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Rename ‘members’ to ‘constituents’
systemd: check service.name.Type and service.name.Restart
bash: change shell script option types from string to lines
installation-cd-base: export mountPoint=/mnt. This doesn't change the default behavior, but an explicit
mount point specification is cleaner.
Add more jobs to the "tested" aggregate
"with pkgs.lib.types; X" -> types.X
Remove $mountPoint

I just don't see the reason for setting this globally, given that /mnt
is the default.
Fix mousepad
xfce: Add tango-icon-theme

The Rodent icon theme depends on ("inherits") Tango.
libvirtd-service: give access to users in the "libvirtd" group

Currently only root has access. But with this patch all users in
"libvirtd" group will have access. This is similar to how it's done on
Ubuntu.

Also, add virtualisation.libvirtd.extraConfig option for further
customization of libvirtd.conf.
networkmanager: Add option for overriding DNS settings

If the option is enabled, the DNS servers from networking.nameservers
will be inserted in /etc/resolv.con and override any DNS servers that
NetworkManager receieves by DHCP, or that is configured manually
in the connection settings.
Add libvirtd gid
libvirtd-service: document that users in "libvirtd" group have access
Add /etc/ssl/certs/ca-certificates.crt symlink for Ubuntu compatibility

NixOS and Fedora uses .../ca-bundle.crt. Ubuntu uses
.../ca-certificates.crt. Add .../ca-certificates.crt symlink to be
compatible with Ubuntu.

Example use case: Bob has a ~/.msmtprc file that he brings over from
Ubuntu. It also works on NixOS.
Revert "Add /etc/ssl/certs/ca-certificates.crt symlink for Ubuntu compatibility"

This reverts commit 10133f0b5b30e4d36a0c66742e1483d126d86f28.

See discussion at https://github.com/NixOS/nixos/pull/224
try to fix zfs into initrd