Add alertlistener example

tools/plex-alertlistener.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Listen to plex alerts and print them to the console.
+Because we're using print as a function, example only works in Python3.
+"""
+import time
+from plexapi.server import PlexServer
+
+
+def _print(msg):
+    print(msg)
+
+
+if __name__ == '__main__':
+    try:
+        plex = PlexServer()
+        listener = plex.startAlertListener(_print)
+        while True:
+            time.sleep(1)
+    except KeyboardInterrupt:
+        listener.stop()