Throw SourceDestination in rename validation.
Fix scheduler hz logic.
Debug log is not tied to scheduler hz.

Now uses a fixed 5 second interval regardless of the configured hz.
Include db info in debug log.
Call delExpiredKeys() in scheduler tick.
Add expire and expireat handlers.
Add persist command.
Add ttl command handler.
Enable pttl command handler.
Enable pexpire command.
Enable the pexpireat command.
Fix process.removeAllListeners() issue.

Stopped coverage from being collected due to istanbul listening for the
exit event.
0.1.49