Merge pull request #2 from chrisdecker1201/bug/missing_initalize_exclude_properties

initialize exclude properties

Author: jcapellman

src/NLog.Targets.Fluentd/Fluentd.cs

@@ -371,6 +371,7 @@ public Fluentd()
             this.LingerTime = 1000;
             this.EmitStackTraceWhenAvailable = false;
             this.Tag = Assembly.GetCallingAssembly().GetName().Name;
+            this.ExcludeProperties = new HashSet<string>();
         }
     }
 }