title: Socket IO send to specified user ID
body: <p>I want to send data to the specified user, and no one else.</p>
  
  <p>currently to broadcast to everyone I do:</p>
  
  <pre><code>socket.on('newChatMessage', function (message) {
  socket.broadcast.emit('newChatMessage_response', { data: message});
  });
  </code></pre>
  
  <p>now what I want to do is simply something like:</p>
  
  <pre><code>socket.on('newChatMessage', function (message) {
  socket.to(5).send('newChatMessage_response', { data: message});
  });
  </code></pre>
  
  <p>to(5) would be the user with the ID of 5.</p>