Added python example

utils/nats/helloworld/README.md

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+Hello World NATS example
+
+# helloworld2.py
+* run `pip install nats-client`
+* run `pip install protobuf`
+
+

utils/nats/helloworld/helloworld2.py

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+# coding: utf-8
+import tornado.ioloop
+import tornado.gen
+import time
+import sys
+sys.path.insert(0, "../../../protobuf/python/proto")
+from datetime import datetime
+from nats.io.utils  import new_inbox
+from nats.io import Client as NATS
+import message_pb2
+
+@tornado.gen.coroutine
+def main():
+    nc = NATS()
+
+    # Establish connection to the server.
+    options = { "verbose": True, "servers": ["nats://127.0.0.1:4222"] }
+    yield nc.connect(**options)
+
+    def discover(msg=None):
+        channel_message = message_pb2.ChannelMessage()
+        channel_message.ParseFromString(msg.data)
+        print("[Received]: %s" % channel_message)
+    
+
+    send_message = message_pb2.ChannelMessage()
+    send_message.chan_num = 5
+    #send_message.from = "python"
+    send_message.message = "Hello, World!"
+
+    sid = yield nc.subscribe("world.channel_message", "", discover)
+
+    yield nc.publish("world.channel_message", send_message.SerializeToString())
+
+    loop = tornado.ioloop.IOLoop.instance()
+    yield tornado.gen.Task(loop.add_timeout, time.time() + 20)
+    try:
+        start = datetime.now()
+        # Make roundtrip to the server and timeout after 1 second
+        yield nc.flush(1)
+        end = datetime.now()
+        print("Latency: %d µs" % (end.microsecond - start.microsecond))
+    except tornado.gen.TimeoutError, e:
+        print("Timeout! Roundtrip too slow...")
+
+if __name__ == '__main__':
+    tornado.ioloop.IOLoop.instance().run_sync(main)