Allow the ability to flush any remaining logs that are buffered and haven't been sent

[jakejscott]

If using the BufferedSumoLogicAppender when it shuts down logs are not being flushed at all. With this fix you can get all the IFlushable objects and call flush on them.

public static void Main()
        {
            try
            {
                int numMessages = 3;
                for (int i = 0; i < numMessages; i++)
                {
                    log4netLog.Info("info " + i);
                }
            }
            finally
            {
                FlushLogs();
            }

            Console.ReadKey();
        }

        private static void FlushLogs()
        {
            var appenderSkeletons = LogManager
                .GetAllRepositories()
                .SelectMany(r => r.GetAppenders())
                .OfType<IFlushable>()
                .ToArray();

            foreach (var appender in appenderSkeletons)
            {
                try
                {
                    appender.Flush(10000);
                }
                catch
                {
                    // Cannot do anything here
                }
            }
        }

[bin3377]

Thanks for the contribution! The change is make sense for me. I will do some test and merge it

[jakejscott]

Are you going to publish a new nuget package?

[bin3377]

yes. it's on https://www.nuget.org/packages/SumoLogic.Logging.Serilog/ now but I think I may push another version to do some adjustment like using consistent version number format...

[jakejscott]

This commit was a change for log4net :) Which hasn't been updated yet in Nuget https://www.nuget.org/packages/SumoLogic.Logging.Log4Net/

[bin3377]

ahh... sorry I just confused myself. Yes, will push a new version for all packages after I fix the appveyor building and couple of doc nits

[bin3377]

FYI - 1.0.0.8 nuget released with this change