maint(sys-apps/systemd): Refresh live ebuild, remove old.

Apply changes made upstream to our live ebuild. Adds a ssl use flag and
removes tcp wrappers support. Remove old 210 live ebuild.
bump(sys-apps/systemd): bump to the latest release
fix(sys-apps/systemd): Fix networkd crash
churn(coreos-base/coreos-cloudinit): Move units into cloudinit repo.
bump(coreos-base/coreos-init): Deprecate old addon units.
fix(coreos-base/oem-rackspace): Rely on generic configdrive units.

Config drive is now supported on all VM platforms so it doesn't need to
be in the rackspace OEM any more.
fix(coreos-base/oem-vagrant): Use generic cloud config unit.
bump(coreos-base/coreos-cloudinit): relax deps in unit files
Merge pull request #547 from marineam/units2

Generic config drive
bump(sys-kernel/coreos-kernel) update to 3.13.10
Merge pull request #548 from gregkh/kernel_update

bump(sys-kernel/coreos-kernel) update to 3.13.10
bump(sys-kernel/bootengine): Add experimental diskless btrfs support.
Merge pull request #549 from marineam/tmpbtrfs

bump(sys-kernel/bootengine): Add experimental diskless btrfs support.
Merge pull request #536 from marineam/systemd

Systemd 212
cleanup(sys-apps/systemd): Remove unused files.

These are installed by gentoo-systemd-integration these days.
fix(sys-apps/systemd): Don't prune systemd dirs

Assorted config directories in /etc are normally empty but without them
users generally have no idea that they can actually use them. Switch to
installing them again and add tmpfiles rules to recreate them.
Merge pull request #550 from marineam/systemd

Minor systemd fixes
bump(sys-apps/baselayout): Include sbin in path
bump(coreos-base/coreos-init): Fix sshd host key generation
Merge pull request #551 from marineam/updates

Updates