This commit adds the `--dev` argument to the `substrate-node` to allow
the chain to keep advancing as time goes own. We have found that if this
option is not added then the chain won't advance forward.
This commit updates how logging is done in the differential testing
harness to use `tracing` instead of using the `log` crate. This allows
us to be able to better associate logs with the cases being executed
which makes it easier to debug and understand what the harness is doing.
Omar