pkgs: Add grandpa version 0.5.

This is going to be needed as the main application for my lighting
laptop :-)

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
common: Factor out common workstation options.

Those options reside now in common-workstation.nix but it's only a
preliminary step, in the long term I guess we want to have this as
modular as possible.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
network: Add new machine "kzerza".

This is another USB flash drive that is used for booting directly into
GrandPA, currently in use at Rockfabrik Augsburg.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>