title: How to specify namespace for sending message to googlecast receiver app
body: <p>I tried webapp sampler of conneckSDK.
  I can launch a googlecast custom receiver app without any problem.
  But when it sending message to receiver, the receiver app expected to get message with specific namespace,  for example 'urn:x-cast:com.google.cast.sample.helloworld' </p>
  
  <p>Plz anyone tell me how to specify the name space in sender app with connectSDK?  Thanks!</p>