Logging loop

If FluentLogger is used as an appender with logback (such as https://github.com/sndyuk/logback-more-appenders) then any logging by FluentLogger and related classes such as RawSocketSender can end up creating a nice little logging loop.

For instance, RawSocketSender will log "Created messages" or a message when the buffer is full... all of which get routed _back_ into slf4j and then likely routed right back into FluentLogger for logging....

While the obvious answer is to drop any org.fluentd.logger.\* messages that would end up routed to the FluentLogger appender (thereby possibly leaving them routed to other appends) that would then mask any real messages but I wonder if there is a better solution?

I don't have any ideas but figured I'd throw the problem out there and maybe someone would have a good idea.

It may also be helpful to enable some type of throttling on messages--- like if the buffer is full due to a down fluentd.

Also cross posted here: https://github.com/sndyuk/logback-more-appenders/issues/2