SyslogUdpHandler - Allow setting "rfc" parameter

[gwinn]

The SyslogUdpHandler constructor has a last parameter "rfc", default value is "self::RFC5424".
However, the current Monolog Bundle implementation dos not allows to set another value like self::RFC3164.

It will be nice if we can do something like that:

monolog:
    handlers:
        syslog:
            type: syslogudp
            host: 127.0.0.1
            port: 514
            level: error
            ident: app
            rfc: 0

[Tobion]

Ref PR #343

[HontoNoRoger]

Also highly requested from my side, need it to select RFC5424e (time with miliseconds) for SyslogUDP logging.