Add DHCP support for remote syslog

Reviewed By: dustin

Add the option to log to remote syslog servers.  The syslog servers
are specified via DHCP response option 7, which is the 'log-servers'
option in ISC DHPC.

Tested using ISC DHCP server option 'log-servers', using multiple
remote syslog servers.

Also tested against syslog-ng and rsyslogd servers.

Also tested changing the DHPC configure in the middle of the discovery
process.  The system reacted as expected, killing the old syslogd
process and starting a new one with the updated remote syslog parameters.