* make the poc work with external runners
* add cwd and don't hardcode the path to the js runner / tests
* Send StartTestRun and StopTestRun in the agent.
* Add a PUSH/PULL in the agent itself.
* This allows to send stopTestRun just once, when all the tests are done.
* Count the number of tests finished before ending.
* We want to stop when all the agents have finished.
* Have a different receiving socket for each agent.
* use json.dumps explicitely in the code.