Use build script from payload if one is provided

This allows us to move the compilation of build scripts to hub, which
again means that updating travis-build doesn't require us to update all
the workers, allowing for quicker and more easy deployments of
travis-build.
update travis-build
Make Travis::Worker::Instance specs pass
Fix Config spec
Fix Factory spec
Fixed Buffer spec
Point staging to the apt cache branch.
Bump travis-build.

Includes a fix for a quote sign that snuck in unseen.
Bump travis-build.

Includes fixes for apt and npm.
Bump travis-build.
Include host names in config for the build.
It's hosts, not host_names.
Bump travis-build.
Bump travis-build back to master.
Bump travis-build.

Includes a little echo to show that we're setting up the APT cache.
Merge branch 'staging'

Conflicts:
	Gemfile.lock
Bump travis-build to diff. branch.
Bump travis-build.

Includes change from token to repo_token for CC.
whitespace
improved vm shutdown

- added the job_id to the hostname
- added retries for vm shutdown when talking to the bb api
- added more logging for errors
- added an 'ensure' to nil off the ssh connection