Consider not calling disconnect on the connection in LogglyAppender

[robmoore]

We are seeing deadlock issues where we are using LogglyAppender wrapped in an AsyncAppender. I was reviewing the LogglyAppender code to see if there's anything that might account for it there and noticed that connection.disconnect() is being called. From the Javadocs (http://docs.oracle.com/javase/7/docs/api/java/net/HttpURLConnection.html#disconnect()), it looks like it might be worth considering not calling disconnect as the docs suggest it is a hint to connection that "Indicates that other requests to the server are unlikely in the near future". It's unclear what effect calling disconnect() will have but it seems in a case like ours where we are sending logging entries to Loggly frequently that it might be causing us to incur unnecessary overhead.

[tony19]

I'm not sure that omitting the call to #disconnect() is the answer as that could cause a resource leak. Perhaps we could provide an option to cache the connection and call #disconnect() only when stopping the appender (similar to the behavior of SocketAppender).