Add a stress test

[PeterKraus]

This stress test runs several short jobs in a row using the example_counter driver. In the current iteration, the pipeline is loaded, 5 jobs are submitted, and then the pipeline is marked as ready.

The intention of this test is:

• to test multiple jobs running on the same pipeline,
• ensure jobs are executed in order of increasing job.id, closing Submitting queued jobs may not be robust #88,
• measure the overhead of job submission and execution