Feature/181 integration tests

the run_integration_test allows us to launch a complete test:

• starts the network component
• starts a clean node with a dataset defined by a json file
• starts a researcher. The researcher command can be a python, python_otebook or any executable (this allows to encapsulate a researcher run into a bash or even simulate a researcher with only MQTT messages (eg: to test failures))

The script works both on macOSX and Linux (please test it on linux strongly than I did !)