Clean up the terminal output and log progress for benchmarks

When developing a new benchmark with geode-benchmarks or testing out code changes interactively, it would be nice to for the geode-benchmarks to log the current throughput and latency numbers as the test is running, similar to the way YCSB does.

This lets someone writing a new benchmark quickly eyeball if the performance has changed, or if their warm up time is too short or too long because the throughput fluctuates.