job status: remove deprecated deployedHosts field

This field should not be in use anywhere.
Clean up Travis scripts and config

* Some spacing to make things more readable.

* Move a random export that was somehow in .travis.yml into .travis.sh,
  where the rest of them are.
[README] update production readiness
Merge pull request #100 from spotify/drewc/readme-update-re-prod

[README] update production readiness
[maven-release-plugin] prepare release 0.0.33
[maven-release-plugin] prepare for next development iteration
[release] only push the release tag

Do not push all tags, just the one we merged to relese.
Merge pull request #101 from spotify/rohan/travis

Clean up Travis scripts and config
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.
Merge pull request #102 from spotify/drewc/push-only-new-tag

[release] only push the release tag
Merge pull request #103 from spotify/rculbertson/job-delete-response

HeliosClient should not return null, when deleting nonexistent job
[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.
Merge pull request #80 from spotify/dano/remove-deprecated-job-status-field

job status: remove deprecated deployedHosts field
Merge pull request #105 from spotify/philipcristiano/jenkins-release

Remove Teamcity's required release branch
Merge pull request #107 from spotify/rohan/exit-code

Workaround incorrect exit code when using LXC
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.
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.

* Add a circle build profile.

* Add circle.sh to make and run socat. We should talk to the Circle guys to
  see if they can expose Docker via TCP so we don't have to do this.