Merge remote-tracking branch 'square/master'

* square/master:
  Reduce duplicated code
  Unregister metrics when stopping monitoring them
  Get better logging from composite verifier process (#1139)
  remove debugging lines
  chase a theory
  force trusty
  lsb-release?
  sudo is useful
  more os hackery
  debug info, prepurge runit as cargocult, and then install its systemd unit file too
  Empty commit to trigger build.