adding logstash UDP appender

examples/logstashUDP.js

@@ -0,0 +1,39 @@
+var log4js = require('../lib/log4js');
+
+/*
+ Sample logstash config:
+   udp {
+    codec => json
+    port => 10001
+    queue_size => 2
+    workers => 2
+    type => myAppType
+  }
+*/
+
+log4js.configure({
+  "appenders": [
+    {
+      type: "console",
+      category: "myLogger"
+    },
+    {
+      "host": "127.0.0.1",
+      "port": 10001,
+      "type": "logstashUDP",
+      "logType": "myAppType", // Optional, defaults to 'category'
+      "fields": {             // Optional, will be added to the 'fields' object in logstash
+        "field1": "value1",
+        "field2": "value2"
+      },
+      "layout": {
+        "type": "pattern",
+        "pattern": "%m"
+      },
+      "category": "myLogger"
+    }
+  ]
+});
+
+var logger = log4js.getLogger("myLogger");
+logger.info("Test log message %s", "arg1", "arg2");