CI: Develop a test harness for a worker (RSS022-73)

[WilliamPetit]

1. Build the harness "framework"
2. Define some tests
3. Test on some big data sets

[WilliamPetit]

I've made some progress with this.
I've configured Maven to run the integration test for datavault-worker
I've created a new test which feed RabbitMQ with some task and listen the messages sent onto the "datavault-events" channel t make sure the worker is doing his job.
Once completed, it checks the created tar file.

I've tested it on my machine and it seemed to work fine but there seems to be some problem when the test run on Travis.