title: Can RocketMQ producer send message with mutiple tags?
body: <p>RocketMQ consumers can subscribe topic with multiple tags like this</p>
  
  <pre><code>consumer.subscribe("topic", "taga||tagb");
  </code></pre>
  
  <p>How can producers send messages with both <code>taga</code> and <code>tagb</code></p>
  
  <p>I have try to send message with tags "taga||tagb", but the consumer does not receive any message. When I query message by the msg_id, the tags is <code>[taga||tagb]</code>, not ["taga", "tagb"]</p>
  
  <pre><code>Topic:               handy_test
  Tags:                [taga||tagb]
  Keys:                [key_1491988576642]
  Queue ID:            0
  Queue Offset:        215
  CommitLog Offset:    36094
  Reconsume Times:     0
  Born Timestamp:      2017-04-12 17:16:16,645
  Store Timestamp:     2017-04-12 17:16:25,316
  Born Host:           10.1.101.16:33421
  Store Host:          10.116.22.25:10911
  System Flag:         0
  Properties:          {TAGS=taga||tagb, KEYS=key_1491988576642}
  </code></pre>