pkgs: Add spectrum2 and dependencies.

We're using the latest Git version here, because 2.0.0-beta2 depends on
a very old boost version, which i didn't want to include. So, as soon as
the next release is finished, we switch over to that.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
hydra: Update submodule to latest Git master.

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