Log Aggregation

Consolidating the log aggregation changes into a single branch with all the conflicts resolved.

Changes:
 * add `--syslog` option to send collected logs to syslog (only available if node-syslog installs)
 * add `--no-timestamp-workers` and `--no-timestamp-supervisor` for toggling log line timestamping
 * add support for giving a piped command to `--log` (eg. `--log '| logger -t "pid:%p worker:%w"'`)
 * cleanup some stream bugs by upgrading to a fully pipe-capable strong-log-transformer
 * update README.md to reflect some changes in behaviour

Remaining:
 * [x] Adjust early logging behaviour as per #21
 * [x] Update README.md to reflect the state of logging in this branch
and process ID (for consistency with worker ID)