Syslog facility (PRI) should be configurable

[tomikaa87]

esp-iot-base/src/Logger.cpp

Line 89 in 30ea180

payload.printf("<191>1 %04u-%02u-%02uT%02u:%02u:%02uZ %s (%s) %s %s - %s",

PRI numbers: https://tools.ietf.org/html/rfc3164#section-4.1.1