Some configuration tweaks

Make the following additional settings configurable (via env vars
indicated):
 * log.flush.interval.messages (FLUSH_INTERVAL_MSGS)
 * log.flush.interval.ms (FLUSH_INTERVAL_MS)
 * num.network.threads (NUM_THREADS)
 * num.io.threads (NUM_THREADS)

Also cleaned up some formatting/style issues
Merge pull request #2 from signalfuse/config-tweaks

Some configuration tweaks