Send buffered logs to Loggly after timeout

In cases of low log volume, it's possible to have logs live in the buffer for an extended period of time. I've added an additional parameter that defines a timeout (in ms) after which the buffered logs will automatically be sent to Loggly. The timeout is reset each time a log is created.

I added the timeout as an additional parameter, as opposed to accepting a buffering options object, for backwards compatibility.