Buffered Appender to reduce number of requests to prevent tcp-port exhaustion

Sending a message to loggly for every message being logged can lead to tcp-port exhaustion and wreak havoc on a server.

This PR adds a `BufferedLogglyAppender` that collects messages and flushes the buffer:
   1. When the buffer reaches a certain size
   2. Periodically after a certain time

To reduce the number of connections made to loggly it uses loggly's bulk endpoint.