title: Rails actioncable alias request origins
body: <p>I have an application with subdomains and I would like to be able to connect to a WebSocket of all of the subdomains when I add a subdomain to
  <code>cable/config.ru</code></p>
  
  <pre><code>ActionCable.server.config.allowed_request_origins = ["domain.com",
   "sub1.domain.com", "sub1.domain.com"]
  </code></pre>
  
  <p>It works ok but how I can set alias for all subdomains 
  somethink like this:</p>
  
  <pre><code>"[*.domain.com]"   
  </code></pre>
  
  <p>Char " * "dosn't work.</p>