Add log traces to MoquetteIdleTimeoutHandler and to NettyAcceptor.

Fix NettyAcceptor shutdown: when the event loops take too long to stop, an IllegalStateException is raised. This leads to leaks, and prevents other
parts of the broker to be shut down properly.

broker/src/main/java/io/moquette/server/netty/MoquetteIdleTimeoutHandler.java

@@ -15,6 +15,9 @@
  */
 package io.moquette.server.netty;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import io.netty.channel.ChannelDuplexHandler;
 import io.netty.channel.ChannelHandler.Sharable;
 import io.netty.channel.ChannelHandlerContext;
@@ -23,16 +26,24 @@ import io.netty.handler.timeout.IdleStateEvent;
 
 @Sharable
 class MoquetteIdleTimeoutHandler extends ChannelDuplexHandler {
+	
+	private static final Logger LOG = LoggerFactory.getLogger(MoquetteIdleTimeoutHandler.class);
+	
     @Override
     public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
         if (evt instanceof IdleStateEvent) {
             IdleState e = ((IdleStateEvent) evt).state();
             if (e == IdleState.ALL_IDLE) {
+            	LOG.info("Firing channel inactive event. MqttClientId = {}.", NettyUtils.clientID(ctx.channel()));
                 //fire a channelInactive to trigger publish of Will
                 ctx.fireChannelInactive();
                 ctx.close();
             }
         } else {
+        	if (LOG.isDebugEnabled()) {
+	        	LOG.debug("Firing Netty event. MqttClientId = {}, eventClass = {}.", NettyUtils.clientID(ctx.channel()),
+						evt.getClass().getName());
+        	}
             super.userEventTriggered(ctx, evt);
         }
     }