title: how to start new proactive conversation dialog without ending to current ongoing dialog
body: <ul>
  <li>SDK Language: <code>Node.js</code></li>
  <li>SDK Version: 3.6</li>
  <li>Development Environment:
  
  <ul>
  <li>Node.js: 6.9.5</li>
  <li>npm version: 4.5.0</li>
  </ul></li>
  </ul>
  
  <h3>Issue Description</h3>
  
  <p>Let's say the user is currently doing conversation with bot, In between, we want to send some survey to the user through proactive message (bot to the user). After feeling survey user should get back the old conversation state, from which point he started the survey.</p>
  
  <p>Or in simple words how to start new proactive conversation dialog without ending to current ongoing dialog</p>