title: Amazon SNS silent pushes
body: <p>In <a href="https://github.com/aws/aws-sdk-ruby" rel="nofollow">aws-sdk</a> gem and Amazon developer docs I tried to find any information about <code>SNS</code> silent pushes, but it seems very contradictorily. 
  I am confusing that in SNS Client message is required, but is it possible to send exactly silent GCM and APNS notifications?</p>
  
  <p>Does anybody have information about it? 
  Any advice/resource will be appreciated.</p>