Using job-scoped environment variables

[ess]

Given a valid job with env vars specified in a jobs file, when I pass that jobs file to cronenberg, the job should be run on its schedule, and the env vars configured for the job should be present. Also, job-scoped env vars take precedence over those specified in the calling environment.

Consider the following job:

- name: env-test
  command: echo $FOO
  when: "* * * * *"
  env:
    FOO: bar-job

Whether or not the shell from which cronenberg is launched has a FOO variable set, the output of this job should be "bar-job"