Add support for multiple open syslogs to SyslogLogger.

Change-Id: I2e1a078d17174d10069483f5894f59c05c02e5fd
Reviewed-on: https://gerrit.causes.com/19165
Reviewed-by: David Gouldin <david.gouldin@causes.com>
Tested-by: Jeremy Dunck <jeremy.dunck@causes.com>