ParseNginx function needs rework

[MartinMachl]

The ParseNginx() function in include/functions should not fail when checking access and/or error logs if the entries are referencing a syslog server.

[MartinMachl]

This update for example would solve the issue
if ! $(echo ${VALUE} | grep -Pq 'syslog:server') && [ ! -f ${VALUE} -a ! -f "${CONFIG_FILE%nginx.conf}${VALUE}" ]; then
LogText "Result: could not find log file ${VALUE} referenced in nginx configuration"
NGINX_ACCESS_LOG_MISSING=1
fi