Expand the syntax on JobResult to be able to state the type of result.

You can now easily state a JobResult is a json file path.

Change-Id: I17fdb27086b6ac1f8395a8327533540356fa588a
Update unit tests with new JobResult api.

Change-Id: I346701f1815f1061b229d3e86c778e2c1023d49e
Update example workers to use new JobResult syntax.

Change-Id: I6ebd493d12bbfcb498b1b1d75268ab87c4569541
Merge branch 'expanded_job_results'

Change-Id: I395bcf507e075a4ad97011b6845c26f98ec595a4