coreos: add ipset, for use with iptables

Note: for now we don't have any units to save/restore ipset data. We may
need to modify the current iptables units so looking into ipsets should
be included as part of that work.
coreos-kernel: bump to 3.15.5
Merge pull request #731 from gregkh/kernel_update

coreos-kernel: bump to 3.15.5
coreos-base/oem-rackspace-teeth: Make cloudinit drop-in an actual unit

This will guarentee that cloudinit reloads systemd's unit files.
Also, fix the ordering on the config-drive mount.
coreos-base/oem-rackspace-teeth: Add pingout service
Merge pull request #729 from marineam/ipset

coreos: add ipset, for use with iptables
networkd: Emulate old kernel naming

The old kernel names are handed out by netname.sh which is called by
79-netname.rules. rename-network-interfaces.service does the rename by
stopping networkd, taking down the interfaces, re-adding the interfaces,
and then restarting networkd.
Merge pull request #730 from crawford/teeth

coreos-base/oem-rackspace-teeth: Add support for network
coreos-base/oem-rackspace-teeth: bump to v0.0.2
updatectl: bump to 1.2.0
Merge pull request #732 from marineam/updatectl

updatectl: bump to 1.2.0
coreos-cloudinit: bump to 0.8.9
locksmith: bump to 0.1.5
Merge pull request #733 from marineam/env

Version bumps
Merge pull request #735 from crawford/master

coreos-base/oem-rackspace-teeth: bump to v0.0.2
systemd: stabilize 215, include bug fixes from upstream.
app-emulation/docker: bump to 1.1.1
Merge pull request #737 from carmstrong/docker-1.1.1

app-emulation/docker: bump to 1.1.1
update_engine: add support for proxy configuration

Details here: https://github.com/coreos/update_engine/pull/37
Merge pull request #739 from marineam/update

update_engine: add support for proxy configuration