job status: remove deprecated deployedHosts field

This field should not be in use anywhere.
[release] only push the release tag

Do not push all tags, just the one we merged to relese.
HeliosClient should return JobDeleteResponse, not null, when deleting nonexistent job

Currently if you try to delete a nonexistent job, HeliosClient returns null,
so the caller doesn't know what happened. This caused a NPE in TemporaryJobs,
because it tried to delete a nonexistent job, and didn't expect the client to
return null. It now returns JobDeleteResponse with the status set to
JOB_NOT_FOUND so the caller can decide if this should be handled as an error
or not.
[release] Remove `release` branch

Our internal release process required a release branch for teamcity. We no longer need this and will help with the new release process where this could cause a problem
Workaround incorrect exit code when using LXC

When an LXC container is killed via docker kill, the exit code is 0 instead
of -1.
Workaround for btrfs issue with removing containers

When using btrfs in certain environments (like CircleCI), the btrfs driver
throws an exception when attempting to remove a container. However, the
container does actually get removed.

Check for this specific case in our tests. This should only affect
AgentRestartTest, since it is the only thing that actually attempts to
remove a container.
[deploy] fix so it properly can deploy to sonatype
[Vagrantfile] skydns fixes and stuff

Make it so that the name argument to the agent is a name,
so when it gets registered in skydns it's not weird.

Also point local dns to the skydns server and register the
machine name (ubuntu-14) in it.
Add support for CircleCI

CircleCI gives us faster, more reliable builds than Travis, since it has a
higher memory limit (4G vs 2G) and also has Docker running natively, rather
than us having to hack it into a usermode Linux instance.

* Add circle.yml configuration. It sets environment variables, ensures that
  Docker is exposed via TCP, and runs our Maven commands.

* Add a circle build profile.
Move gpg signing to profile

So that you don't need to have the keys just to build/install anything.
Also done as profile because if we just removed the <executions> it has
been observed to produce bad GPG signatures.
Collect artifacts for CircleCI

Collect generated Debian packages, and any JAR's that end in a version or
snapshot number (that is, not sources, javadoc, or shaded).
CircleCI: Add parallelism for tests

Also move stuff into circle.sh since it's more complicated now and hard to
express in yaml.