Add Datacenters to the JobListStub struct

e2e tests for upgrade path to driver plugins

* master: (23 commits)
  tests: avoid assertion in goroutine
  spell check
  ci: run checkscripts
  tests: deflake TestRktDriver_StartWaitRecoverWaitStop
  drivers/rkt: Remove unused github.com/rkt/rkt
  drivers/rkt: allow development on non-linux
  cli: Hide `nomad docker_logger` from help output
  api: test api and structs are in sync
  goimports until make check is happy
  nil check node resources to prevent panic
  tr: use context in as select statement
  move pluginutils -> helper/pluginutils
  vet
  goimports
  gofmt
  Split hclspec
  move hclutils
  Driver tests do not use hcl2/hcl, hclspec, or hclutils
  move reattach config
  loader and singleton
  ...

Document devices

Co-Authored-By: dadgar <alex@hashicorp.com>

Merge branch 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad into f-driver-upgradepath-test

* 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad:

drivers: add docker upgrade path and e2e test

Merge branch 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad into f-driver-upgradepath-test

* 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad:
  Apply suggestions from code review

ci: run seperate build jobs for slower packages

Fix bug related to high cpu usage

Co-Authored-By: nickethier <ncethier@gmail.com>

Grab bag of small changes

`travis.sh` contained some bash-ism despite it being invoked with `sh`.

Avoid depending on OS-specific library for some simple structs.

cli: Hide `nomad docker_logger` from help output

Add some tests to ensure that api/structs values are in sync.

Given that vendoring libraries prune tests by default, test dependencies
aren't leaked to clients of the package - so it should be safe to add
such dependency without affecting api clients.

Make plugins/shared external and make pluginutls/

Don't emit task events after alloc is in a terminal DesiredState