Show traceback / call trace of failed transactions when running tests

[iamdefinitelyahuman]

The design is poor and the logging settings in config.json are very confusing. This area can be improved upon greatly.

[iamdefinitelyahuman]

I think the best approach here is:

• remove logging from the config file, do not allow any permanent verbosity modifications in this way
• expand the --verbose flag - it should be possible to automatically output the traceback and/or call trace on failed transactions, especially when running tests (include a note that this will come at a time expense because of debug_traceTransaction)