Test suite

Added a lot of docstring and other documentation in the test suite. This is based on my limited understanding, as well as comments by @ouziel-slama and @adamkrellenstein .
Would that be better?
```
    """
    Run the integration tests. 
    Reads scenario.py to get all the integration scenarios to create a holistic integration test run,
    executes it and then compares the json, sql and log output with data in 'scenarios/' folder.
    """
```