add an expiration to the worker heartbeat messages
Merge branch 'master' of https://github.com/travis-ci/travis-worker
bundle update

travis-build, along with some smaller libs
requeue job if there are build infrastucture issues

if there is no log output, and the ssh connection can not be closed
cleanly, this usually points to a build infrastucture issue so the job
should be requeued
split up the create_new_server method a little

this is a tiny bit of clean up, and the first step before adding more
metrics