fix(coreos-base/coreos-base): Remove old ChromeOS files.

The udev rules are required on our system and refer to non-existent
groups causing udev to spew a bit of useless noise on boot.

The profile.d scripts don't do anything at all.
fix(coreos-base/coreos-base): Update users and groups.

Remove the following unused users/groups:
 - core-access
 - polkituser
 - pkcs11
 - ipsec
 - tor
 - tcpdump
 - debugd
 - openvpn
 - input

Add groups:
 - docker (new group, for things like access to docker socket)
 - systemd-journal (exists in sdk, not images. for journal log access)
 - dialout (exists in sdk, required by default udev rules)

The core user has access to docker and systemd-journal.
fix(coreos-base/coreos-base): Remove directory creation.

This duplicates sys-apps/baselayout so don't bother. Probably left over
from when baselayout wasn't properly installed with the 'build' use flag
to initialize the filesystem tree.
fix(coreos-base/coreos-base): Change core's shell to bash.

It is bash but might as well be explicit about that.
fix(coreos-base/coreos-base): Install sysctl, a little more cleanup.

Pair down the old unused sysctl.conf do what is useful for us and
install it into /usr/lib/sysctl.d for systemd to handle.

Installing /srv in the SDK does no harm so do so.

EAPI=5 because, better.
fix(app-emulation/docker): Remove old ebuilds, remove sysctl call.

ipv4 forwarding is now enabled in coreos-base via a sysctl config.