#151 Support sending logs to syslog

[Phil]

Hi!
Logs on embedded devices are often kept in a ring buffer and never written to disc (which remains read-only). To facilitate this, running software should log via syslog instead of trying to maintain log files themselves.
I have a patch which makes minidlna fall back to syslog if log_dir variable remains empty, but am not sure if this suits the expected config style. I could think of accepting the string "syslog" instead so the default value of /var/log remains.
What do you think? If optional log output to syslog is fine with you, please just let me know how users are supposed to enable it. I'll follow up with an appropriate patch.
Thanks, Phil