feat(sys-kernel/coreos-kernel): Enable VFIO modules

Original thread:
https://groups.google.com/forum/#!topic/coreos-dev/MGxSfJNdNkM
bump(sys-kernel/coreos-kernel): Bump revision, cleanup old ebuilds.
Merge pull request #369 from marineam/vfio

Enable VFIO
fix(sys-apps/dbus): Add slot dependency on systemd

This will force a recompile of dbus when systemd's sub-slot changes as
it did from 207->209 when some lib versions changed.
clean(sys-apps/dbus): Remove unused ebuilds
fix(sys-apps/baselayout): Use custom script to generate /etc/group

I misunderstood the documentation for systemd-tmpfiles, if a string to
write to a file is provided it will always write it, even if the file
already exists and doesn't need to be created. This means that using
tmpfiles to initialize /etc/group results appending each boot.

Instead use a little script instead, also initialize passwd and shadow
so that the `passwd` command works for the core user.

Make use of the systemd eclass where applicable.
bump(sys-apps/systemd): sync live ebuild with upstream + local changes

This pulls in the latest changes from Gentoo as of 21 Feb 2014 along
with the CoreOS changes we made in the 207 ebuild.

Hard mask kdbus flag. We don't need to tread into those waters yet.

We will be trying networkd but leave the flag disabled until someone
wants to start working with it.
fix(sys-apps/systemd): Fix a few upstream changes/issues. Add 209.

- Restore openrc use flag, we don't want to pull it in.
- Change cpp #if LIVE to bash if statements to symlinks work.
- Depend on a newer libseccomp, build fails with old versions.
- Depend on lxml if python is enabled.
- Add version 209!
fix(sys-apps/systemd): Patch pkg-config instead of enabling compat libs.

Enabling compat libs is causing ld errors. To keep things like dbus
compiling we can instead just provide the old pkg-config files.

Patch from https://bugs.gentoo.org/show_bug.cgi?id=501860