[feature] Automate run after plan (with check-index)

As life is all about doing as less repetitive work as possible, automation is key.
If Nomad job descriptor files are to be templated, the first thought is using `consul-template`. But then: why not automate the execution of `run` and `plan` too?

The beauty of the Nomad 2 stage `plan` -> `run` idea, is that the `check-index` returned by `plan`, should give enough confidence to automatically go on with the `run`.
But.... I don't see any option (without any stdout scraping hacks) to automatically pass the `check-index` from `plan` to `run`.

Would it be an idea to either add for instance a `-run-on-success` parameter to the `plan` command?
Anther option would be to give the `run` command an option to write the `check-index` to a state file, which can be used as input to the `run` command (thinking that this can be enhanced to remote plan/run state management like in Terraform).

Any thoughts?