Feature/181 integration tests

the script can run multiple nodes now.

Validated on mnist test:

./scripts/run_integration_test -s ./notebooks/getting-started.py -d tests/datasets/mnist.json -d tests/datasets/mnist.json -d tests/datasets/mnist.json -d tests/datasets/mnist.json -d tests/datasets/mnist.json -d tests/datasets/mnist.json -d tests/datasets/mnist.json